Activation and expansion of T-cells using an engineered multivalent signaling platform as a research tool

ABSTRACT

Provided are a system and methods for selectively inducing expansion of a population of T cells in the absence of exogenous growth factors, such as lymphokines, and accessory cells for research purposes. The cell based expansion system and methods permit the long-term growth of CTLs, preferably human CTLs. In addition, T cell proliferation can be induced without the need for antigen, thus providing an expanded T cell population that is polyclonal with respect to antigen reactivity. Further provided are methods for using the system and methods to screen and identify antigens related to specific diseases or conditions, tumors, autoimmune disorders, or an infectious disease or pathogen, and to identify target molecule for research purposes, or for developing a vaccine based thereon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.10/336,224 now U.S. Pat. No. 7,638,325, filed Jan. 3, 2003, and U.S.application Ser. No. 10/336,135, filed Jan. 3, 2003, which in turnclaims the benefit of priority under 35 U.S.C. §119 (e) to U.S.Provisional Patent Application 60/346,092, filed Jan. 3, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to methods for stimulating andactivating cells, and more particularly, to methods to activate andexpand cells using an engineered multivalent signaling platform. Thepresent invention also relates to methods for generating engineeredmultivalent signaling platform and methods of using same.

2. Description of the Related Art

Immunotherapy involving the priming and expansion of T lymphocytes (Tcells) holds promise for the treatment of cancer and infectiousdiseases, particularly in humans (Melief et al., Immunol. Rev. 145:167-177 (1995); Riddell et al., Annu. Rev. Immunol. 13:545-586 (1995)).Current studies of adoptive transfer in patients with HIV, CMV, andmelanoma involve the infusion of T cells that have been stimulated,cloned and expanded for many weeks in vitro on autologous dendriticcells (DC), virally infected B cells, and/or allogeneic feeder cells(Riddell et al., Science 257:238-241 (1992); Yee et al., J. Exp. Med.192:1637-1644 (2000), Brodie et al., Nat. Med. 5:34-41 (1999); Riddellet al., Hum. Gene Ther. 3:319-338 (1992), Riddell et al., J. Immunol.Methods 128:189-201 (1990)). However, adoptive T cell immunotherapyclinical trials commonly use billions of cells (Riddell et al., 1995).In order to produce these quantities of cells, many fold expansion of Tcells in vitro (e.g., 40 population doublings) is usually required.Furthermore, for optimal engraftment potential and possible therapeuticbenefit, it is important to ensure that the T cells, after in vitroexpansion, are functional, and not senescent, at the time ofre-infusion.

Naturally occurring T cell activation is initiated by the engagement ofthe T cell receptor/CD3 complex (TCR/CD3) by a peptide-antigen bound toa major histocompatibility complex (MHC) molecule on the surface of anantigen-presenting cell (APC) (Schwartz, Science 248:1349 (1990)). Whilethis is the primary signal in T cell activation, other receptor-ligandinteractions between APCs and T cells are required for completeactivation. For example, TCR stimulation in the absence of othermolecular interactions can induce a state of anergy, such that thesecells cannot respond to full activation signals upon restimulation(Schwartz, 1990; Harding, et al., Nature 356:607 (1992)). In thealternative, T cells may die by programmed cell death (apoptosis) whenactivated by TCR engagement alone (Webb et al., Cell 63:1249 (1990);Kawabe et al., Nature 349:245 (1991); Kabelitz et al., Int. Immunol.4:1381 (1992); Groux et al., Eur J. Immunol. 23:1623 (1993)).

Multiple receptor-ligand interactions take place between the T cell andthe APC, many of which are adhesive in nature, reinforcing the contactbetween the two cells (Springer et al., Ann. Rev. Immunol. 5:223(1987)), while other interactions transduce additional activationsignals to the T cell (Bierer et al., Adv. Cancer Res. 56:49 (1991)).For example, CD28 is a surface, glycoprotein present on 80% ofperipheral T cells in humans and is present on both resting andactivated T cells. CD28 binds to B7-1 (CD80) or B7-2 (CD86) and is themost potent of the known co-stimulatory molecules (June et al., Immunol.Today 15:321 (1994), Linsley et al., Ann. Rev. Immunol. 11:191 (1993)).CD28 ligation on T cells in conjunction with TCR engagement induces theproduction of interleukin-2 (IL-2) (June et al., 1994; Jenkins et al.,1993; Schwartz, 1992). While the exact in vivo role of IL-2 is still inquestion, there is little doubt that IL-2 is a critical factor for exvivo T cell expansion (Smith et al., Ann. N.Y. Acad. Sci. 332:423-432(1979); Gillis et al., Nature 268:154-156 (1977)).

Recently, several new co-stimulatory molecules have been discoveredbased on their homology with the B7 and CD28 families. PD-1 is expressedon activated T cells and has two B7 like ligands, PD-L1 and PD-L2.Presently, it is unclear whether PD-1 ligation delivers an inhibitory(Freeman et al., J. Exp. Med. 192: 1027-1034 (2000); Latchman et al.,Nat. Immunol. 2:261-268 (2001)) or co-stimulatory signal (Dong et al.,Nat. Med. 5:1365-1369 (1999); Tseng et al., J. Exp. Med. 193:839-846(2001)) to T cells. B7-H3, which does not bind to CD28, CTLA-4, ICOS orPD-1, may act as a co-stimulatory molecule for T cell activation andIFN-γ production (Chapoval et al., Nat. Immunol. 2:269-274 (2001)).

The TNF receptor family member 4-1BB (CD137) was initially identified inreceptor screens of activated lymphocytes (Pollok, K. E. et al., T cellJ. Immunol. 150, 771-781 (1993)). The 4-1BB ligand is expressed byactivated B cells, dendritic cells, and monocytes/macrophages, all ofwhich can act as APCs (Goodwin, R. G et al., T cell Eur. J. Immunol. 23,2631-2641 (1993)). Previous studies have shown that 4-1BB is aco-stimulatory molecule in the activation of T cells, and its signalingis independent from, albeit weaker than, CD28 signaling (Hurtado, J. C.,et al., T cell J. Immunol. 158, 2600-2609 (1997); Hurtado, J. C., etal., T cell J. Immunol. 155, 3360-3367 (1995); Saoulli, K. et al., Tcell J. Exp. Med. 187, 1849-1862 (1998)). 4-1BB stimulationpreferentially activates CD8⁺ T cells in vitro and amplifies generationof CTL responses in vivo (Shuford, W. W. et al, T cell T cell J. Exp.Med. 186, 47-55 (1997)). The mechanism for this effect may involveimproved survival of activated CTLs (Takahashi, C., et al., T cell J.Immunol. 162, 5037-5040 (1999)). Consistent with these data,co-stimulation of 4-1BB has been shown to have anti-viral and anti-tumoreffects (Tan, J. T. et al., J. Immunol. 164, 2320-2325 (2000); Melero,I. et al., T cell Nat. Med. 3, 682-685 (1997); Melero, I. et al., Eur J.Immunol. 28, 1116-1121 (1998); DeBenedette, M. A., et al., J. Immunol.158, 551-559 (1997); Guinn, B. A., et al., J. Immunol. 162, 5003-5010(1999)).

Co-stimulation of T cells has been shown to affect multiple aspects of Tcell activation (June et al., 1994, Supra). It lowers the concentrationof anti-CD3 required to induce a proliferative response in culture(Gimmi et al., Proc. Natl. Acad. Sci. USA 88:6575 (1991)). CD28co-stimulation also markedly enhances the production of lymphokines byhelper T cells through transcriptional and post-transcriptionalregulation of gene expression Lindsten et al., Science 244:339 (1989);Fraser et al., Science 251:313 (1991)), and can activate the cytolyticpotential of cytotoxic T cells. Inhibition of CD28 co-stimulation invivo can block xenograft rejection, and allograft rejection issignificantly delayed (Lenschow et, al., Science 257:789 (1992); Turkaet al., Proc. Natl. Acad. Sci. USA 89:11102 (1992)).

Methods of expanding T cell clones and/or lines for adoptiveimmunotherapy have proven to have certain drawbacks. The standardculture of pure CD8⁺ cells is limited by apoptosis, diminution ofbiological function and/or proliferation, and obtaining a sufficientnumber of cells to be useful has been particularly difficult. Currentcell culture techniques may require several months to produce sufficientnumbers of cells from a single clone (Riddell et al., 1992; Heslop etal., Nat. Med. 2:551-555 (1996)), which is a problematic limiting factorin the setting of malignancy. Indeed, it is possible that such the Tcells that are currently infused into patients, may have a limitedreplicative capacity, and therefore, could not stably engraft to providelong-term protection from disease. Furthermore, the various techniquesavailable for expanding human T cells have relied primarily on the useof accessory cells (i.e. cells that support or promote T cell survivaland proliferation such as PBMC or DC, B cells, monocytes, etc.) and/orexogenous growth factors, such as interleukin-2 (IL-2). IL-2 has beenused together with an anti-CD3 antibody to stimulate T cellproliferation. Both primary and secondary APC signals are thought to berequired for optimal T cell activation, expansion, and long-termsurvival of the T cells upon re-infusion. The requirement for accessorycells presents a significant problem for long-term culture systemsbecause these cells are relatively short-lived. Therefore, in along-term culture system, APCs must be continually obtained from asource and replenished. The necessity for a renewable supply ofaccessory cells is problematic for treatment of immunodeficiencies inwhich accessory cells are affected. In addition, when treating viralinfection, if accessory cells carry the virus, the cells may contaminatethe entire T cell population during long-term culture.

In the absence of exogenous growth factors or accessory cells, aco-stimulatory signal may be delivered to a T cell population, forexample, by exposing the cells to a CD3 ligand and a CD28 ligandattached to a solid phase surface, such as a bead. See C. June, et al,(U.S. Pat. Nos. 5,858,358 and 6,352,694); C. June et al., WO 99/953823.The methods currently available in the art have not focused on obtaininga more robust population of T cells and the beneficial results thereof.Furthermore, the applicability of activated and expanded T cells hasbeen limited to only a few disease states. For maximum in vivoeffectiveness, theoretically, an ex vivo- or in vivo-generated,activated T cell population should be in a state that can maximallyorchestrate an immune response to cancer, infectious disease, or otherdisease states. While previous investigators have noted long termqualitative persistence of T cells in human adoptive transfer protocols,the quantitative level of sustained engraftment has been low (Rosenberget al., N. Engl. J. Med. 323:570-578 (1990); Dudley et al., J.Immunother. 24:363-373 (2001); Yee et al., Curr. Opin. Immunol.13:141-146 (2001); Rooney et al., Blood 92:1549-1555 (1998)).

Therefore, the present invention offers therapeutic advantages becausethere remains an unmet need for sustained high-level engraftment ofhuman T lymphocytes. Methods of stimulating the expansion of certainsubsets of T cells have the potential to generate a variety of T cellcompositions useful in immunotherapy. Successful immunotherapy can beaided by increasing the reactivity and quantity of T cells by efficientstimulation. The present invention provides methods to generate anincreased number of activated and pure T cells that have surfacereceptor and cytokine production characteristics that are optimal for Tcell-mediated immune responses and that appear more physiologicallyfunctional than T cells produced by other expansion methods. Inaddition, the present invention provides compositions of cellpopulations of any target cell, including T cell populations andparameters for producing the same, as well as providing other relatedadvantages.

BRIEF SUMMARY OF THE INVENTION

The present invention provides engineered multivalent signalingplatforms (EMSP) for use as a research tool in stimulation and/orexpansion of T cells. To this end, one of ordinary skill in the artwould understand that a variety of combinations of the elements of thepresent invention is easily identifiable. For instance, T cells eitherstimulated and/or expanded can be used for therapeutic purposes.

In one aspect, the present invention is directed to stimulation,activation, or expansion of T cells, including but not limited to CD4⁺and CD8⁺ T cells. Further, the present invention finds particularbenefit in the ability to sequentially stimulate and expand CD8⁺ cellswithout a significant loss in viability and maintaining function of theCD8⁺ T cells after multiple rounds of stimulation with EMSPs.

In another aspect, the present invention provides an engineeredmultivalent signaling platform (EMSP) for use in stimulating and/oractivating T cells for research use, comprising an EMSP that expressesor displays on its surface one or more agents that ligate a cell surfacemoiety of at least a portion of T cells and stimulates said T cells. Incertain embodiments this platform may comprise a cell line. This cellline may be a mammalian cell line, including, but not limited to, humancell lines. In certain embodiments the cell line displays low or noendogenous MHC as compared with typical antigen presenting cells. Anantigen presenting cell refers to those cells that normally initiate theresponses of naïve and/or memory T cells to antigen. Illustrative APCsinclude, but are not limited to, dendritic cells (DC), macrophages, andB cells. In related embodiments, the human cell line may be K562, U937,721.221, T2, and C1R cells.

It is a further aspect to provide methods for producing the APC forresearch purposes and a system of use thereof.

In related aspects, the EMSPs of the present invention are cells thatare genetically modified to express a human Fcγ receptor or manipulatedto have this receptor bound to the surface of the EMSP. In certainembodiments the receptor comprises CD32. In an alternative embodiment,the EMSP are genetically modified to express a membrane bound ScFv, orfragment thereof, or other membrane-bound form of antibody, that iscapable of capturing or otherwise binding secondary antibodies, orfragments thereof. Within this context, the EMSP becomes “armed” withthese secondary antibodies, such as anti-CD3, anti-CD28, or anti-41BBantibodies. In other embodiments, the EMSP is a cell that is geneticallymodified to express CD32 and said one or more agent is an antibody thatbinds to a cell surface molecule on the surface of T cells. Alsoprovided are the presently described EMSPs wherein the EMSP is furthergenetically modified to express or manipulated to display aco-stimulatory molecule for a T cell. In certain embodiments theco-stimulatory molecule may be any one of or a combination of CD80,CD86, 4-1BBL, OX40L, ICOS-L, ICAM, PD-L1 and PD-L2. Other embodimentsinclude but are not limited to EMSPs wherein one or more agent on thesurface is an antibody that is displayed on the surface of said EMSP viainteraction with the Fcγ receptor. Other embodiments, of course includewherein the one or more agent displayed or expressed on the EMSP is anatural ligand for a T cell such as those to CD28 and 4-1BB.

In certain aspects the present invention also provides EMSPs in the formof cells or cell lines that have been genetically modified to expressstimulatory agents, co-stimulatory agents, and/or cytokines as well asother polypeptides. When cytokines are expressed any of those desired bybe utilized. For example, IL-2, IL-15, GM-CSF, IL-4, TNF-α, and/or IFN-γbe utilized among others.

In yet additional embodiments, the source of T cells to be stimulated,activated, and/or expanded by use of the EMSPs may be any type of Tcell, including CD4⁺, CD8⁺, regulatory T cells and the like.

Also provided by the instant invention are EMSPs that display or expresson their surface antibodies such as anti-CD3 and anti-CD28 antibodies aswell as or alternatively, other ligands and stimulatory orco-stimulatory molecules such as 4-1BB ligand.

In other aspects the present invention provides methods for activatingand/or stimulating a population of T cells by cell surface moietyligation, comprising providing a population of cells wherein at least aportion thereof comprises T cells; contacting said population of cellswith an EMSP, said EMSP having on its surface one or more agents thatligate a cell surface moiety of at least a portion of said T cells andactivates or stimulates said T cells. In certain embodiments the EMSPcomprises a cell. In related embodiments the cell may be a mammaliancell, the cell may be a human cell, the cell may be a murine cell, thecell may be from a cell line such as a human cell line. In furtherembodiments the T cells are expanded by culturing the cells followingstimulation with EMSPs under conditions and for time sufficient toprovide expansion. Such expansion may occur in the presence or absenceof EMSPs as well as in the presence or absence of exogenously addedcytokines. Further, such stimulation and/or expansion may occur in vivo.In related embodiments the method includes separating said T cells fromsaid EMSP and subsequently incubating said T cells with an agent thatfacilitates T cell expansion. Those of skill in the art would appreciatethat the T cells stimulated or expanded may be derived from any sourceincluding but not limited to a patient, from a T cell line, or from a Tcell clone.

In yet additional aspects the present invention provides methods formaintaining or restoring T cell repertoire, such as the Vβ repertoire ofselect T cell populations to be expanded, by stimulating with the EMSPsof the invention for a time sufficient to induce activation andsubsequently expanding said T cells. In certain embodiments theexpansion occurs in the presence or absence of EMSPs.

In further related aspects, the EMSPs of the present invention may beused to maintain the viability of T cells during culture, even followingmultiple/sequential rounds of stimulation. In certain embodimentssequential rounds of stimulation may be initiated by EMSPs. In certainaspects, even following sequential stimulation of T cells, such aswithout limitation CD8⁺ T cells, the viability of said T cells isgreater than 50%, 60%, 70%, 80%, or 90% following at least one, two,three, four, five, six, seven, or eight rounds of stimulation.

In certain aspects of the present invention, EMSP may be used foractivating and/or stimulating a population of T cells as describedherein in conjunction with other surfaces, such as but not limited to,beads. In one embodiment, EMSP may be used to activate and/or stimulatea population of T cells for one or more rounds of stimulation, followedby one or more rounds of stimulation using paramagnetic beads, such asdescribed in U.S. patent application Ser. No. 10/350,305. In a furtherembodiment, EMSP may be used to activate and/or stimulate a populationof T cells following activation and/or stimulation using beads, such asthose described in U.S. patent application Ser. No. 10/350,305.

In certain embodiments, CD8⁺ T cells re-stimulated with the EMSP of thepresent invention have reduced levels of apoptosis as compared tostimulation using other methods. Thus, the present invention alsoprovides methods for enhancing survival of a population of CD8⁺ T cells,comprising stimulating said cells at least once with EMSP, said EMSPhaving on its surface at least one primary stimulatory agent and atleast one co-stimulatory agent. In certain embodiments, the CD8⁺ T cellsare expanded in the presence or absence of said EMSP. In furtherembodiments, the CD8⁺ T cells demonstrate an increase in Bcl-X_(L)levels compared to CD8⁺ T cells expanded in the absence of initialstimulation with said EMSP. In certain embodiments, the increase is fromabout 1.5 fold to about 10 fold and higher. In certain embodiments, theincrease is about 15, 20, 30, 40, or 50 fold in expression. In oneembodiment, the increase in Bcl-X_(L) expression is from about 2, 2.5,3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 fold or higher.In yet additional embodiments the EMSP expresses or displays a 4-1BBligand. In other embodiments the EMSP displays or expresses an agentthat binds to CD3 or other components of the TCR/CD3 complex, and anagent that binds to CD28 or an agent that binds 4-1BB or any combinationor multiple thereof. In related embodiments sequential stimulation withthe EMSP also demonstrates decrease in apoptosis as compared to cellssequentially stimulated by other means such as by anti-CD3 and anti-CD28coated beads. A decrease generally means a decrease in apoptosis incells stimulated with the EMSP of the present invention as compared tocells stimulated by other means, as measured using any number of assaysknown in the art and described herein. In certain embodiments, thedecrease is from about 1.5 fold to about 10 fold and lower. In certainembodiments, the decrease is about 15, 20, 30, 40, or 50 fold lowerapoptosis observed. In one embodiment, the decrease in apoptosis isabout 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5fold lower in cells stimulated with the EMSP of the present invention.

Apoptosis is a basic physiological process that plays a major role inthe regulation of cell populations. Methods for measuring apoptosis arewell known in the art. Apoptosis can be determined by methods such as,for example, DNA ladder, electron or light microscopy, flow cytometry,and different commercially available kits for the determination ofapoptosis. Within the context of this invention, decreases or increasesin apoptosis can be measured using any number of assays known to theskilled artisan. Illustrative assays include but are not limited to,measuring gene expression levels of Bcl-xL or other apoptosis genes, andfluorescent staining with Annexin V and propidium iodide.

In further aspects the present invention also provides methods forexpanding a population of T cells by cell surface moiety ligation. Inaddition, it is an object to provide a method of inducing a populationof T cells from a subject to rapidly proliferate exponentially for along term to sufficient numbers for research purposes, comprisingisolating a population of T cells from a subject, activating thepopulation of T cells by contacting the T cells ex vivo with at leastone exogenous first agent that provides a primary activation signal tothe T cells, and stimulating the activated T cells with at least onesecond agent that provides a co-stimulatory signal, such that T cellsthat have received a primary activation signal are stimulated to rapidlyproliferate. In particular, it is an object to provide such a methodwhen the subject is human, and wherein the method further comprisesusing the activated T cells to identify antigens in the subject.Moreover, when the subject is infected with a disease or condition,having at least one antigen related thereto, the provided method furthercomprises using the activated T cells to identify the at least oneantigen. The antigen may comprise, e.g., and without limitation, a tumorantigen, an antigen relating to an autoimmune disorder or condition, oran infectious disease or pathogen. The method further comprisesscreening the at least one antigen as a target molecule for researchpurposes, or for developing a vaccine based upon the at least oneantigen.

In yet additional embodiments the EMSP comprises a cell, such as amammalian cell (e.g., human, murine, etc.). The cell may be from a cellline. In some embodiments, at least one round of stimulation isprovided. In related embodiments sequential rounds of stimulating said Tcells are performed with EMSP either by previously purifying T cellsfrom originally added EMSP and subsequently adding additional EMSP or byadding additional EMSP to previously stimulated cells without separationof originally added EMSP. In other embodiments, the T cells areseparated from said EMSP and subsequently incubated with an agent thatfacilitates T cell expansion, followed by restimulation with EMSP. Ofcourse the T cells for these methods could be derived from any sourceincluding PBMC, purified T cells, T cell lines, T cell clones, etc. Incertain embodiments the EMSP comprises a cell displaying ligands for anyone of CD3 and/or TCR complex (such as peptide-MHC complexes), CD28, or4-1BB including any combination thereof, such as ligands to all three.

One aspect of the present invention provides a population of T cellsexpanded by the methods of the present invention either in the absenceor presence of exogenous cytokines and wherein said T cells aresubstantially free of EMSP.

One additional aspect of the invention comprises a method for increasinguptake of an exogenously added nucleic acid molecule in T cells,comprising contacting said T cells with an EMSP and contacting said Tcells with said nucleic acid molecule thereby, said contacting of EMSPwith said T cells rendering cells more amenable to uptake of nucleicacid. In one embodiment of the invention, exogenously added nucleicacids are operably linked to a promoter. In certain embodiments, nucleicacid molecules provided herein provide gene replacement for abnormalgene products.

In certain aspects of the present invention, the natural functionalityof said T cells is preserved following stimulation and expansion usingthe methods provided herein.

In another aspect of the invention, a method of activating antigenspecific T cells is provided comprising contacting a population of Tcells with an antigen and an EMSP under conditions and for timesufficient to induce activation of T cells specific to said antigen. Incertain embodiments, a population of T cells is first contacted withantigen, and then contacted with EMSP. Antigen-specific cells for use inexpansion using the EMSP of the present invention may also be generatedin vitro using any number of methods known in the art, for example, asdescribed in U.S. Patent Application No. 60/469,122 entitled, GENERATIONAND ISOLATION OF ANTIGEN-SPECIFIC T CELLS, filed May 8, 2003, or in U.S.Pat. Nos. 6,040,177 and 5,872,642. Antigen-specific cells for use inexpansion using the EMSP of the present invention may also be generatedusing any number of methods known in the art, for example, as describedin Current Protocols in Immunology, or Current Protocols in CellBiology, both published by John Wiley & Sons, Inc., Boston, Mass.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description, examples and figures whichfollow, and in part will become apparent to those skilled in the art onexamination of the following, or may be learned by practice of theinvention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. It should be understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown.

FIGS. 1A-1C depict construction of artificial APCs (aAPC) (anillustrative example of an engineered multivalent signaling platform, orEMSP) from the parental K562 cell line. FIG. 1A depicts two-colorflow-cytometric analysis of MHC I and II expression and CD54 and CD58expression in parental K562 cells (top panels). Expression of CD32 and4-1BBL in K32 (left) and K32/4-1BBL (right) cell lines is shown (middlepanels). Isotype controls for the anti-CD32 antibody (IgG2a) andanti-41BBL antibody (IgG1) are shown for each aAPC (bottom panels). FIG.1B depicts the engineered K32/4-1BBL aAPC interacting with a CD8⁺ Tcell. FIG. 1C graphically depicts proliferation of polyclonal CD4⁺ andCD8⁺ T cells stimulated with the indicated aAPCs, measured by[3H]thymidine incorporation between days 3 and 4 culture. T cells werestimulated with aAPCs as indicated, in the absence of cytokines. At 72hours the cells were pulsed with [3H]thymidine and incubated for anadditional 18 hours before harvesting. Counts per minute values areshown as mean±s.e.m. from triplicate cultures.

FIGS. 2A-2C depict long-term growth of primary polyclonal human CD8⁺ Tcells stimulated with aAPCs in the absence of exogenous cytokines. FIG.2A graphically depicts CD8⁺ T cells stimulated with CD3/28 beads (X),irradiated K32 cells loaded with CD3/28 antibodies (Δ), or withirradiated K32/4-1BBL cells loaded with CD3/28 antibodies (•). T cellswere stimulated with aAPCs on days 0, 10, and 20 of culture. FIGS. 2B,2C depict the purity of T cells and the fate of irradiated K32/4-1BBLstimulator cells assessed by staining for CD3, CD8 (FIG. 2B), and CD32(FIG. 2C) expression during the first 7 days of culture. Variablenumbers of red blood cells and platelets were contained in the inputcultures; gating on cell size/debris was not used in this experiment sothat all cells in the culture were represented. Viable cells areindicated by gating on propidium iodide to exclude dead cells. Resultsare representative of >10 different experiments, each with a differentdonor.

FIGS. 3A-3D depict propagation of antigen-specific cytotoxic T cellsfrom an HLAA*0201 donor using K32/4-1BBL aAPCs. FIG. 3A is a schematicof the experimental protocol of the present invention. FIG. 3B depictsthe specificity of cell cultures as assessed by MHC tetramer staining.CD8⁺ T cells were stained with anti-CD8 antibody (x-axis) and A*0201tetrameric MHC (y-axis) loaded with influenza matrix protein peptide(fluMP). Left panel of 3B: initial cell population of T cells on day 0,with gates showing the cells into CD8⁺flu-tet⁺ and CD8⁺flu-tet⁻populations. Right panels of 3A: tetramer staining of CD8⁺flu-tet⁻ (top)or CD8⁺flu-tet⁻ (bottom) cultures after expansion on K32/4-1BBL cellsfor 26 days. FIG. 3C graphically depicts a growth curve of the sortedCD8⁺ T cell populations. T cells were sorted into CD8⁺ fluMP tetramer⁺(•) or CD8⁺ fluMP tetramer⁻ (□). The sorted T cell populations were thenstimulated with irradiated K32/4-1BBL cells loaded with CD3/28antibodies as indicated (arrows). rIL-2 was added to the culturesbeginning on day 28. The total cell numbers are depicted in a semi-logplot of cell number v. days in culture. FIG. 3D graphically depictscytotoxicity of flu-specific T cells after expansion on K32/4-1BBL aAPCsfor 26 days. ⁵¹Cr-release assays were done using TAP-deficient HLAA*0201T2 target cells pulsed (circles) or unpulsed (squares) with the fluMPpeptide. Antigen-specific cytotoxicity was also examined by comparingCD8⁺ fluMP tetramer⁺ cells (closed symbols) to CD8⁺FluMP tetramer⁻ cells(open symbols). Values shown as mean±s.e.m. of triplicate cultures.Y-axis, percentage of specific 51 Cr release; x-axis, effector:target(E:T) ratios. The entire protocol is representative of threeexperiments, each from different donors.

FIG. 4 depicts maintenance of the TCR Vβ repertoire in polyclonal CD8⁺ Tcells after expansion with K32/4-1BBL aAPCs. T cells cultured on K32 orK32/4-1BBL aAPCs from the growth curve shown in FIG. 2 were assessed forthe CDR3 length distribution. The indicated TCR Vβ family is shown atbaseline, and after 17 days of culture.

FIGS. 5A and 5B graphically depict expression of genes involved in Tcell growth and survival after stimulation with aAPCs. Real-timequantitative RT-PCR of Bcl-xL (mean±s.e.m.) (FIG. 5A) or IL-2 (FIG. 5B)mRNA in polyclonal CD8⁺ T cultures. Y-axis:—fold expression of Bcl-xL orIL-2 relative to day 0 of culture. All cultures were stimulated withaAPCs on days 0 and 10. Results are representative of three differentexperiments with different donors.

FIG. 6 depicts the distinct effects on apoptosis in cultures ofpolyclonal human CD8⁺ T cells stimulated with various aAPCs.Flow-cytometric analysis of cultured cells stained with FITC-labeledannexin V (x-axis) and propidium iodide (y-axis). The three rowsrepresent different aAPCs used for stimulation. The columns representdays in culture. All cultures were stimulated with aAPCs on days 0 and10. Data shown are not gated. Results are representative of threeexperiments with different donors.

FIG. 7 shows polyclonal expansion and cell sorting of hTERT 1540⁺ CD8⁺cells from 2 different cancer patient. Two rounds of polyclonalexpansion and tetramer-guided high speed sorting achieved a nearly purepopulation of tetramer⁺ CD8⁺ cells. IFN-γ secretion was analyzed byELISPOT after the first sort. Cytolysis of carcinoma cells OV-7 orSW-480 (HLA-A2⁺, telomerase⁺) and SK-OV-3 (HLA-A2−, telomerase⁺) wasanalyzed after the second sort at an E:T ratio 20:1. For UPIN 906, high-and intermediate-level tetramer-binding T cells were sorted and analyzedseparately.

DETAILED DESCRIPTION OF THE INVENTION

Prior to setting forth the invention, it may be helpful to anunderstanding thereof to set forth definitions of certain terms thatwill be used hereinafter.

The term “biocompatible”, as used herein, refers to the property ofbeing predominantly non-toxic to living cells.

The term “stimulation”, as used herein, refers to a primary responseinduced by ligation of a cell surface moiety. For example, in thecontext of receptors, such stimulation entails the ligation of areceptor and a subsequent signal transduction event. With respect tostimulation of a T cell, such stimulation refers to the ligation of a Tcell surface moiety that in one embodiment subsequently induces a signaltransduction event, such as binding the TCR/CD3 complex. Further, thestimulation event may activate a cell and upregulate or downregulateexpression or secretion of a molecule, such as downregulation of TGF-β.Thus, ligation of cell surface moieties, even in the absence of a directsignal transduction event, may result in the reorganization ofcytoskeletal structures, or in the coalescing of cell surface moieties,each of which could serve to enhance, modify, or alter subsequentcellular responses.

A stimulation cycle or round of stimulation generally refers tostimulation as described herein and the period of culture followingstimulation without any additional stimulation (e.g., restimulation). Astimulation cycle or round of stimulation is generally from about 7-14days. In certain embodiments, the stimulation cycle can be shorter, forexample 2, 3, 4, 5, or 6, days. In certain embodiments, the stimulationcycle can be much longer, such as from 15-20, or from 20-30 days. Incertain embodiments, it may be desirable for the T cells to enter aquiescent, non-dividing phase of the cell cycle. Therefore, in certainembodiments of the present invention, cells may remain in culturewithout restimulation for periods much longer than 10 days, such as for11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and even 40 days in vitro.As described in U.S. Pat. No. 6,040,177, T cells were observed to assumea small round morphology and 60-95% of the cells remained viable (asdetermined by trypan blue dye exclusion) even after 28 days in culture.

The term “activation”, as used herein, refers to the state of a cellfollowing sufficient cell surface moiety ligation to induce a noticeablebiochemical or morphological change. Within the context of T cells, suchactivation refers to the state of a T cell that has been sufficientlystimulated to induce cellular proliferation. Activation of a T cell mayalso induce cytokine production and performance of regulatory orcytolytic effector functions. Within the context of other cells, thisterm infers either up or down regulation of a particularphysico-chemical process The term “activated T cells” indicates T cellsthat are currently undergoing cell division, cytokine production,performance of regulatory or cytolytic effector functions, and/or hasrecently undergone the process of “activation.”

The term “target cell”, as used herein, refers to any cell that isintended to be stimulated by cell surface moiety ligation.

An “antibody”, as used herein, includes both polyclonal and monoclonalantibodies; primatized (i.e., modified to include more primate-specificresidues in a constant region) (e.g., humanized); murine; mouse-human;mouse-primate; and chimeric; and may be an intact molecule, a fragmentthereof (such as scFv, Fv, Fd, Fab, Fab′ and F(ab)′₂ fragments), ormultimers or aggregates of intact molecules and/or fragments; and mayoccur in nature or be produced, e.g., by immunization, synthesis orgenetic engineering; an “antibody fragment,” as used herein, refers tofragments, derived from or related to an antibody, which bind antigenand which in some embodiments may be derivatized to exhibit structuralfeatures that facilitate clearance and uptake, e.g., by theincorporation of galactose residues. This includes, e.g., F(ab),F(ab)′₂, scFv, light chain variable region (V_(L)), heavy chain variableregion (V_(H)), and combinations thereof.

The term “protein”, as used herein, includes proteins, polypeptides andpeptides; and may be an intact molecule, a fragment thereof, ormultimers or aggregates of intact molecules and/or fragments; and mayoccur in nature or be produced, e.g., by synthesis (including chemicaland/or enzymatic) or genetic engineering.

The term “T cell clone” as used herein includes T cells derived from asingle T cell or those having identical TCRs. T cells can be clonedusing numerous methods known in the art including limiting dilutionassays (LDA) and cell sorting using flow cytometry.

The term “T cell line” as used herein includes T cell clones and mixedpopulations of T cells with different TCRs all of which may recognizethe same target (e.g., antigen, tumor, virus).

The term “substantially free of” as used herein means a population ofcells, e.g., T cells, that is at least 50% free of non-T cells, or incertain embodiments at least 60, 70, 80, 85, or 90% free of non-T cells.

The term “agent”, “ligand”, or “agent that binds a cell surface moiety”,as used herein, refers to a molecule that binds to a defined populationof cells. The agent may bind any cell surface moiety, such as areceptor, an antigenic determinant, or other binding site present on thetarget cell population. The agent may be a protein, peptide, antibodyand antibody fragments thereof, fusion proteins, synthetic molecule, anorganic molecule (e.g., a small molecule), a carbohydrate, or the like.Within the specification and in the context of T cell stimulation,antibodies and natural ligands (e.g., B7 and 4-1BBL) are used asprototypical examples of such agents.

The terms “agent that binds a cell surface moiety” and “cell surfacemoiety”, as used herein, are used in the context of a ligand/anti-ligandpair. Accordingly, these molecules should be viewed as acomplementary/anti-complementary set of molecules that demonstratespecific binding, generally of relatively high affinity (an affinityconstant, K_(a), of about 10⁶ M⁻¹).

A “co-stimulatory signal”, as used herein, refers to a signal, which incombination with a primary signal, such as TCR/CD3 ligation, leads to Tcell proliferation and/or upregulation or downregulation of keymolecules.

A “ligand/anti-ligand pair”, as used herein, refers to acomplementary/anti-complementary set of molecules that demonstratespecific binding, generally of relatively high affinity (an affinityconstant, K_(a), of about 10⁶ M⁻¹) Exemplary ligand/anti-ligand pairsenzyme/inhibitor, hapten/antibody, lectin/carbohydrate, ligand/receptor,and biotin/avidin or streptavidin. Within the context of the presentinvention specification receptors and other cell surface moieties areanti-ligands, while agents (e.g., antibodies and antibody fragments)reactive therewith are considered ligands.

“Separation”, as used herein, includes any means of substantiallypurifying one component from another (e.g., by filtration or magneticattraction).

“Quiescent”, as used herein, refers to a cell state wherein the cell isnot actively proliferating.

A “surface”, as used herein, refers to any surface capable of having anagent attached thereto and includes, without limitation, metals, glass,plastics, co-polymers, colloids, lipids, lipid bilayers, cell surfacessuch as EMSP as described herein, and the like. Essentially any surfacethat is capable of retaining an agent bound or attached thereto. Aprototypical example of a surface used herein, is an engineeredmultivalent signaling platform or a particle such as a bead.

“Antigen” as used herein, refers to any molecule 1) capable of beingspecifically recognized, either in its entirety or fragments thereof,and bound by the “idiotypic” portion (antigen-binding region) of a mAbor its derivative; 2) containing peptide sequences which can be bound byMHC molecules and then, in the context of MHC presentation, canspecifically engage its cognate T cell antigen receptor. As such,according to the present invention, the source of antigen may be, but isnot limited to, protein, including glycoprotein, peptides, superantigens(e.g., SEA, SEB, TSST-1) antibody/antigen complexes, tumor lysate,non-soluble cell debris, apoptotic bodies, necrotic cells, whole tumorcells from a tumor or a cell line that have been treated such that theyare unable to continue dividing, allogeneic cells that have been treatedsuch that they are unable to continue dividing, irradiated tumor cells,irradiated allogeneic cells, natural or synthetic complex carbohydrates,lipoproteins, LPS, RNA or a translation product of said RNA, and DNA ora polypeptide encoded by said DNA. Non-transformed cells are typicallyirradiated with gamma rays in the range of about 3000 to 3600 rads, morepreferably at about 3300 rads. Lymphoblastoid or tumor cell lines aretypically irradiated with gamma rays in the range of about 6000 to10,000 rads, more preferably at about 8000 rads. Necrotic and apoptoticcells may be generated by physical, chemical, or biological means.Necrotic cells are typically generated by freeze-thawing, whileapoptotic cells are generated using UV irradiation. UV and gammairradiation, and freeze-thawing procedures are well known in the art andare described, for example, in Current Protocols in Molecular Biology orCurrent Protocols in Immunology, John Wiley & Sons, New York, N.Y.

Generation of Engineered Multivalent Signaling Platforms (EMSP)

One aspect of the present invention is directed to the finding that acell-based universal engineered multivalent signaling platform (EMSP)specifically optimized for rapid expansion of human T cells can be usedto stimulate the long-term growth of functional polyclonal andantigen-specific human T lymphocytes. In particular, in one aspect ofthe present invention, the EMSP can be generated that stimulate thelong-term growth of CD8⁺ T cells. In another aspect of the presentinvention, the EMSP can be generated that stimulate the long-term growthof CD4⁺ T cells. In a further embodiment, the EMSP can be generated tostimulate the long-term growth of regulatory T cells. Similarly, theEMSP of the present invention can be used for stimulation of growth ofcombinations of T cell subsets (e.g., γδ-T cells, CD4⁺ and CD8⁺ ag-specT cells). In yet another embodiment, an EMSP can be generated tostimulate CD4/CD8 double positive T cells, or CD28-negative T cells. Oneillustrative embodiment of an EMSP is referred to as an artificialantigen presenting cell (aAPC) and is described herein in the Examples.

An “engineered multivalent signaling platform (EMSP)”, as used herein,refers to a lipid bilayer engineered (e.g., genetically, physically, orchemically manipulated) to have on its surface at least one moleculecapable of binding to a T-lymphocyte and inducing a primary activationevent and/or a proliferative response or capable of binding a moleculehaving such an affect thereby acting as a scaffold. In one embodiment,the EMSP is engineered to express a molecule that binds to the Fcportion of an antibody. In an additional embodiment, an EMSP comprises acell line engineered to stably express a molecule capable of binding tothe Fc portion of an antibody This universal EMSP can then be loadedwith any variety of antibodies that recognize cell surface moleculespresent on the surface of T lymphocytes, e.g. CD3, or a component of theTCR/CD3 complex, CD28, 4-1BB, TCR, etc. In an alternative embodiment, anEMSP can be generated by directly engineering a cell line to stablyexpress the ligands for cell surface molecules present on the surface ofT lymphocytes, e.g., CD3, or a component of the TCR/CD3 complex, CD28,4-1BB, TCR, etc. The EMSP can be further engineered to stably expressone or more co-stimulatory molecules, for example CD86 or 4-1BB ligand.For example, in one illustrative embodiment of the present invention, anEMSP is engineered to express the human low-affinity Fcγ receptor, CD32and the CD86 molecule. In another illustrative embodiment of the presentinvention an EMSP is engineered to express CD32 and the 4-1BB ligand. Inone embodiment, the EMSP of the present invention can be generated thatexpress membrane bound ScFv or a fragment thereof, that recognize anycell surface molecule of interest, such as CD3, CD28, 41BB and the like,or that recognize other antibodies, such as through binding to the Fcportion. In this regard, the EMSP can be armed with secondary antibodiesthat bind through recognition of the Fc portion. The skilled artisanwould readily recognize that any variety and combination of stimulatoryand/or co-stimulatory molecules can be used in the context of thepresent invention. Further, an EMSP may be engineered to express avariety of molecules useful for the stimulation and activation of Tlymphocytes and/or be loaded with a variety molecules useful for thestimulation and activation of T lymphocytes. In some instances, theexpression of these ligands/receptors could be regulated by “regulatabletranscription promoters”, such a tetracycline dependent promoter, whichcould be an advantage in certain in vivo applications of the K32 line(see Examples) and its derivatives.

In a further embodiment, the EMSP of the present invention areengineered to express an antigen of interest, such as a tumor antigen(e.g., a melanoma, breast tumor, leukemia or other tumor antigen), anauto-antigen (e.g., MBP), a viral antigen (e.g., an HIV, CMV, EBV, orHepatitis antigen) or antigen of other pathogens of interest, presentedon the EMSP surface in the context of MHC. Alternatively, the EMSP ofthe present invention can be pulsed with antigen using any number ofassays known to the skilled artisan, or transduced or otherwise expressMHC which can then be pulsed with peptide/antigen. In yet anotherembodiment, an EMSP of the present invention can be engineered toexpress peptide-MHC tetramers (Altman, et al., Science. 1996 Oct. 4;274(5284):94-6.), or monomers or dimers or trimers. Other illustrativemolecules and methods useful in the context of this invention are asdescribed in U.S. Pat. Nos. 6,001,365, 6,355,479, 5,529,921, and6,464,973; herein incorporated by reference in their entirety.

According to certain methods of the invention, antigen may comprisedefined tumor antigens such as, but not limited to, the melanoma antigenMelan-A (also referred to as melanoma antigen recognized by T cells orMART-1), melanoma antigen-encoding genes 1, 2, and 3 (MAGE-1, -2, -3),melanoma GP100, carcinoembryonic antigen (CEA), the breast cancerantigen, Her-2/Neu, telomerase reverse transcriptase (hTERT), serumprostate specific antigen (PSA), Wilm's Tumor (WT-1), mucin antigens,MUC-1, -2, -3, -4, and B cell lymphoma idiotypes.

Antigen source may also comprise non-transformed, transformed,transfected, or transduced cells or cell lines. Cells may betransformed, transfected, or transduced using any of a variety ofexpression or retroviral vectors known to those of ordinary skill in theart that may be employed to express recombinant antigens. Expression mayalso be achieved in any appropriate host cell that has been transformed,transfected, or transduced with an expression or retroviral vectorcontaining a DNA molecule encoding recombinant antigen(s). Any number oftransfection, transformation, and transduction protocols known to thosein the art may be used, for example those outlined in Current Protocolsin Molecular Biology, John Wiley & Sons, New York, N.Y., or in numerouskits available commercially (e.g., Invitrogen Life Technologies,Carlsbad, Calif.). In one embodiment of the present invention,recombinant vaccinia vectors and cells infected with said vacciniavectors, may be used as a source of antigen. Recombinant antigen mayinclude any number of defined tumor antigens described below.

The EMSP of the present invention may be loaded with antigen orengineered to express a variety of stimulatory, co-stimulatorymolecules, targeting agents, and/or cytokines through geneticmodification. Genetic modification may comprise RNA or DNA transfectionusing any number of techniques known in the art, for exampleelectroporation (using e.g., the Gene Pulser II, BioRad, Richmond,Calif.), various cationic lipids, (LIPOFECTAMINE™, Life Technologies,Carlsbad, Calif.), or other techniques such as calcium phosphatetransfection as described in Current Protocols in Molecular Biology,John Wiley & Sons, New York, N.Y. For example, 5-50 μg of RNA or DNA in500 μl of Opti-MEM can be mixed with a cationic lipid at a concentrationof 10 to 100 μg, and incubated at room temperature for 20 to 30 minutes.Other suitable lipids include LIPOFECTIN™, LIPOFECTAMINE™. The resultingnucleic acid-lipid complex is then added to 1-3×10⁶ cells, preferably2×10⁶, EMSP in a total volume of approximately 2 ml (e.g., in Opti-MEM),and incubated at 37° C. for 2 to 4 hours. The EMSP may also betransduced using viral transduction methodologies as described below.

The EMSP may alternatively be genetically engineered to express avariety of stimulatory molecules, co-stimulatory molecules, cytokines,and/or antigens using retroviral transduction technologies. In oneaspect of the invention, the retroviral vector may be an amphotropicretroviral vector, preferably a vector characterized in that it has along terminal repeat sequence (LTR), e.g., a retroviral vector derivedfrom the Moloney murine leukemia virus (MoMLV), myeloproliferativesarcoma virus (MPSV), murine embryonic stem cell virus (MESV), murinestem cell virus (MSCV), spleen focus forming virus (SFFV), oradeno-associated virus (AAV). Most retroviral vectors are derived frommurine retroviruses. Retroviruses adaptable for use in accordance withthe present invention can, however, be derived from any avian ormammalian cell source. These retroviruses are preferably amphotropic,meaning that they are capable of infecting host cells of severalspecies, including humans. In one embodiment, the gene to be expressedreplaces the retroviral gag, pol and/or env sequences. A number ofillustrative retroviral systems have been described (e.g., U.S. Pat.Nos. 5,219,740, 6,207,453; 5,219,740; Miller and Rosman, BioTechniques7:980-90, 1989; Miller, A. D., Human Gene Therapy 1:5-14, 1990; Scarpaet al., Virology 180:849-52, 1991; Burns et al., Proc. Natl. Acad. Sci.USA 90:8033-37, 1993; and Boris-Lawrie and Temin, Cur Opin. Genet.Develop. 3:102-09, 1993.

The cell line used to generate EMSP can be derived from any mammal.Particularly illustrative cell lines can be derived from human, mouse,monkey, rabbit, or pig cells. In one particular embodiment, the cellline used as a scaffold for the EMSP is a human cell line. Generally,cell lines used to generate an EMSP of the present invention for thegeneration of polyclonal T cells, expresses low or no MHC class I orclass II molecules, although, cloned T cells, or T cells with knownspecificity may not require low MHC on the EMSP, as they will tend notto be allo-responsive, and simply need to be amplified in number. In oneparticular embodiment, the K562 human erythromyloid cell line is used(American Type Culture Collection, Manassas, Va.). In a furtherembodiment, the 721.221 cell line is used as a scaffold for generatingan EMSP (R. Greenwood, et al., 1994. J. Immunol. 153:5525; Shimizu, Y,and R. DeMars. 1989. J. Immunol. 142:3320). In another embodiment, theT2 cell line is used as a scaffold for generating an EMSP (Salter, R.D., et al., 1985. J. Immunol. 135:4235; III Grandea, A. G, et al., 1995.Science 270:105). In yet a further embodiment, the C1R cell line is usedas a scaffold for generating an EMSP (Edwards, P. A., et al., 1982. Eur.J. Immunol. 12:641). Generally, cell lines used to generate an EMSP ofthe present invention for the generation of antigen-specific T cells,can express MHC molecules.

In one aspect of the present invention, lipid bilayers can be used as ascaffold for generating EMSP. Illustrative lipid bilayers are asdescribed for example in Copeland, B., and McConnel, H. M. (1980)Biochim. Biophys. Acta 599, 95-109; McMullen, T. P. W., et al., (1994)Biophys. J. 66, 741-752; Almeida, P. F. F., et al, 1992 Biochemistry 31,7198-7210; Tilcock, C. P. S., et al, 1984, Biochemistry 23, 2696-2703;Simons, K and Ikonen, E. 1997 Nature 387, 569-572; Siminovitch, D. J. etal., 1987, Biochim. Biophys. Acta 901, 191-200.

As discussed above, the EMSP may be engineered to express a variety ofstimulatory molecules, co-stimulatory molecules, cytokines, and/orantigen. The language “nucleic acid molecule encoding such molecules” isintended to include any nucleic acid molecule that will be transcribedand translated into a protein in accordance with the present inventionupon introduction of the nucleic acid molecule into an EMSP (e.g., themolecule can further contain appropriate control elements for regulatingexpression in the EMSP). The nucleic acid molecule encoding thestimulatory, co-stimulatory and/or antigen molecules can consist of onlythe coding region of the corresponding gene, or alternatively it cancontain noncoding regions, such as 5′ or 3′ untranslated regions,introns, fragments thereof, or other sequences.

The nucleic acid molecule can encode the full length marker orco-stimulatory protein or alternatively the nucleic acid can encode apeptidic fragment thereof that is sufficient to confer enhanced cellproliferation in accordance with the present invention, when contactedwith a target cell such as a T cell. The nucleic acid can encode thenatural marker or co-stimulatory protein or fragment thereof, or amodified form of the marker or co-stimulatory protein or fragmentthereof. Modified forms of the natural marker or co-stimulatory proteinthat are within the scope of the invention are described below.

The invention is intended to include the use of fragments, mutants, orvariants (e.g., modified forms) of the marker, stimulatory,co-stimulatory molecule, or antigen protein that retain the ability toinduce stimulation and proliferation of T cells. A “form of the protein”is intended to mean a protein that shares a significant homology withthe natural marker, stimulatory molecule, co-stimulatory protein orantigen and is capable of effecting stimulation and proliferation of Tcells. The terms “biologically active” or “biologically active form ofthe protein,” as used herein, are meant to include forms of marker,stimulatory molecules, or co-stimulatory proteins that are capable ofeffecting enhanced activated T cell proliferation. One skilled in theart can select such forms of markers, stimulatory molecules, orco-stimulatory proteins based on their ability to enhance T cellproliferation upon introduction of a nucleic acid encoding said proteinsinto an EMSP. The ability of a specific form of marker, stimulatoryprotein, co-stimulatory protein or antigen to enhance T cellproliferation can be readily determined, for example, by measuring cellproliferation or effector function by any known assay or method,including many disclosed herein.

The nucleic acid can be a cDNA or alternatively it can be a genomic DNAfragment. Variants of the proteins described herein can be prepared b avariety of known methods, such as, for example, by introducingnucleotide base pair modifications (e.g., substitutions, deletions,additions) to a nucleic acid molecule encoding a protein useful in theinstant invention by standard methods, such as site-directed mutagenesisor polymerase chain reaction-mediated (PCR) mutagenesis.

Furthermore, it will be appreciated by those skilled in the art thatchanges in the primary amino acid sequence of a protein useful in thepresent invention are likely to be tolerated without significantlyimpairing the ability of the protein to enhance T cell proliferation.Accordingly, mutant forms of the proteins that have amino acidsubstitutions, deletions and/or additions as compared to the naturallyoccurring amino acid sequence of a comparable native protein molecule;yet still retain the functional activity of the natural form of theprotein as described herein are also encompassed by the invention. Toretain the functional properties, preferably conservative amino acidsubstitutions are made at one or more amino acid residues. A“conservative amino acid substitution” is one in which the amino acidresidue is replaced with an amino acid residue having a similar sidechain. Families of amino acid residues having similar side chains havebeen defined in the art, including basic side chains (e.g., lysine,arginine, histidine), acidic side chains (e.g., aspartic acid, glutamicacid), uncharged polar side chains (e.g., glycine, asparagine,glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains(e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine,methionine, tryptophan), beta-branched side chains (e.g., threonine,valine, isoleucine) and aromatic side chains (e.g., tyrosine,phenylalanine, tryptophan, histidine).

To express a nucleic acid molecule encoding a desired protein, such asCD32, 4-1BBL, CD86 or other stimulatory or co-stimulatory molecules inan EMSP, the nucleic acid must be operably linked to regulatoryelements. “Operably linked” is intended to mean that the nucleotidesequence encoding the protein of interest is linked to at least oneregulatory sequence in a manner that allows expression of the nucleotidesequence in the EMSP. Regulatory sequences are selected to directexpression of the desired protein in an appropriate EMSP. Accordingly,the term “regulatory sequence” includes promoters, enhancers and otherexpression control elements. Such regulatory sequences are known tothose skilled in the art and are further described in Goeddel, GeneExpression Technology: Methods in Enzymology 185, Academic Press, SanDiego, Calif. (1990).

These regulatory elements include those required for transcription andtranslation of the nucleic acid encoding the marker(s), stimulatorymolecules, co-stimulatory protein(s), and antigen and may includepromoters, enhancers, polyadenylation signals, and other sequencesnecessary for transport of the molecule to the appropriate cellularcompartment, which in certain embodiments, is the outer mitochondrialmembrane (Gonzales-Garcia et al., Development 120:3033 (1994)). When thenucleic acid is a cDNA in a recombinant expression vector, theregulatory functions responsible for transcription and/or translation ofthe cDNA are often provided by viral sequences. Examples of commonlyused viral promoters include those derived from polyoma, adenovirus 2,cytomegalovirus and simian virus 40, and retroviral LTRs (long terminalrepeats).

Regulatory sequences linked to the cDNA can be selected to provideconstitutive or inducible transcription. Inducible transcription can beaccomplished by, for example, use of an inducible enhancer. Thus, in aspecific embodiment of the invention the nucleic acid molecule encodinga desired protein such as CD32, CD28, 4-1BB ligand, CD86 or otherstimulatory or co-stimulatory proteins is under the control of aninducible control element such that expression of the desired proteincan be turned on or off (or intermediate levels in between) using anagent which affects the inducible control element (e.g., expression canbe modulated by modulating the concentration of the inducing agent inthe presence of the T cell). This allows for switching on or off of theexpression of the protein. These regulatory sequences can functioneither in vitro or in vivo. Illustrative inducible or otherwiseregulated expression systems those controlled by heavy metals (Mayo etal, 1982 Cell 29:99-108), RU-486 (a progesterone antagonist) (Wang etal., 1994 Proc. Natl. Acad. Sci. USA 91:8180-8184), steroids (Mader andWhite, 1993 Proc. Natl. Acad. Sci. USA 90:5603-5607), and tetracycline(Gossen and Bujard 1992 Proc. Natl. Acad. Sci. USA 89:5547-5551, U.S.Pat. No. 5,464,758). Thus, inducible expression of a variety of proteinsuseful in the present invention can be used in vivo for production of agene therapy product. Likewise, an inducible expression system can beused to transduce or transfect a population of T cells, eitherpolyclonal, antigen-specific, clonal, or T cell lines, which can then beinfused in a patient and further induced in vivo to express a desiredprotein. In an additional embodiment, the EMSP of the present inventioncan be modified with a gene under the control of inducible expressioncontrol element. These EMSP can then also be administered to a patientand induced in vivo to express a desired protein. Within this and othercontexts of the present invention, the induced EMSP can be used to breaktolerance against tumor antigens, autoantigens, or other pathogenicantigens such as viral antigens. The EMSP of the present invention canalso be used to break tolerance in vitro, as described herein, wherebythe T cells are then infused into a patient. In another embodiment, EMSPor T cells of the present invention can be transfected or transducedwith a gene encoding a homing molecule or other so called “addressins”under the control of an inducible expression element. Such modified EMSPor activated T cells can then be induced in vivo or in vitro. Such EMSPor T cells expressing the induced gene would then be used to home to aparticular site of interest, for example a site of tumor or otherdisease such as autoimmune disease or viral infection. The skilledartisan would readily recognize that any variety of proteins would beuseful under the control of an inducible expression control element orpromoter, e.g., cytokines, homing receptors, addressing, tumor antigens,viral antigens, or other proteins useful for the recruitment of otherimmune cells to a site such as a lymph node, for destruction oractivation.

The EMSP of the present invention are generally irradiated or otherwiserendered non-dividing prior to contact with target cells such that theEMSP are no longer dividing. In one embodiment of the present invention,the EMSPs are irradiated with 100 Gy (10,000 rads). However, one ofskill in the art would readily recognize that the amount of irradiationcan be optimized according to the type of EMSP. Also, other chemicalmethods could serve the same function, such as formamide fixation, ormitomycin C, for example. In embodiments where synthesized lipidbilayers are used as a scaffold for generating EMSP, the skilled artisanwould recognize that treatments such as irradiation are not necessary.Further, treatment to render the EMSP non-viable or non-dividing isunnecessary when such cells are to be removed by selection or othermeans prior to infusion.

The source of EMSP can be autologous, allogeneic, syngeneic, xenogeneic,or chemically synthesized. In another embodiment, the cells can bederived from a product of cell fusion or a cell hybrid (e.g., fusions ofcells inter or intra species).

The EMSP can be stored under a variety of conditions, such as at roomtemperature, 4° C., cryopreserved, or freeze-dried. The EMSPs can alsobe fixed using any number of common fixatives such as formaldehyde orformamide.

The agents can be added to the EMSP before, during or after mixing withtarget cells.

The EMSP of the present invention can be used in in vitro or in vivosettings. For example, EMSP can be administered in vivo at local tumorsites or disease sites or can be administered systemically. As describedfurther below, pharmaceutical compositions comprising the EMSP of thepresent invention are administered via any variety of routes and dosesand can be determined by the skilled artisan. EMSP can be loaded withligands/Abs in vivo by systemic or local administration following adminof EMSP. Similarly, ligand and/or ligand receptor can be induced to beexpressed following transfer using drugs, such as tetracycline, to driveexpression off of inducible gene elements.

Generally, T cells of the present invention are first stimulatedresulting in upregulation and/or downregulation of certain key moleculesfollowed by or concomitant with exit from the G0 phase. Subsequently,these T cells can be expanded to large numbers using a variety ofdifferent molecules as described herein below.

Sources of T Cells

In one aspect of the present invention, ex vivo T cell expansion can beperformed by isolation of T cells and subsequent stimulation followed byfurther expansion. In one embodiment of the invention, the T cells maybe stimulated by a single agent. In another embodiment, T cells arestimulated with two agents, one that induces a primary signal and asecond that is a co-stimulatory signal. Ligands useful for stimulating asingle signal or stimulating a primary signal and an accessory moleculethat stimulates a second signal may be used in soluble form, attached tothe surface of a cell, such as an EMSP, or immobilized on a surface asdescribed herein. In a preferred embodiment both primary and secondaryagents are co-immobilized on a surface, for example a bead or an EMSP.In one embodiment, the molecule providing the primary activation signal,such as a CD3 ligand, and the co-stimulatory molecule, such as a CD28ligand or 4-1BB ligand are coupled to or loaded on the same surface, forexample, a particle or an EMSP. Further, as noted earlier, one, two, ormore stimulatory molecules may be used on the same or differing surfacesor EMSP.

Prior to expansion, a source of T cells is obtained from a subject. Theterm “subject” is intended to include living organisms in which animmune response can be elicited (e.g., mammals). Examples of subjectsinclude humans, dogs, cats, mice, rats, and transgenic species thereof Tcells can be obtained from a number of sources, including peripheralblood mononuclear cells, bone marrow, lymph node tissue, spleen tissue,and tumors. In certain embodiments of the present invention, any numberof T cell lines available in the art, may be used. In certainembodiments of the present invention, T cells can be obtained from aunit of blood collected from a subject using any number of techniquesknown to the skilled artisan, such as Ficoll separation. In onepreferred embodiment, cells from the circulating blood of an individualare obtained by apheresis or leukapheresis. The apheresis producttypically contains lymphocytes, including T cells, monocytes,granulocytes, B cells, other nucleated white blood cells, red bloodcells, and platelets. In one embodiment, the cells collected byapheresis may be washed to remove the plasma fraction and to place thecells in an appropriate buffer or media for subsequent processing steps.In one embodiment of the invention, the cells are washed with phosphatebuffered saline (PBS). In an alternative embodiment, the wash solutionlacks calcium and may lack magnesium or may lack many if not alldivalent cations. Initial activation steps in the absence of calciumlead to magnified activation. As those of ordinary skill in the artwould readily appreciate a washing step may be accomplished by methodsknown to those in the art, such as by using a semi-automated“flow-through” centrifuge (for example, the Cobe 2991 cell processor)according to the manufacturer's instructions. After washing, the cellsmay be resuspended in a variety of biocompatible buffers, such as, forexample, Ca-free, Mg-free PBS. Alternatively, the undesirable componentsof the apheresis sample may be removed and the cells directlyresuspended in culture media.

In another embodiment, T cells are isolated from peripheral bloodlymphocytes by lysing the red blood cells and depleting the monocytes,for example, by centrifugation through a PERCOLL™ gradient. A specificsubpopulation of T cells, such as CD28⁺, CD4⁺, CD8⁺, CD45RA⁺, andCD45RO⁺T cells, can be further isolated by positive or negativeselection techniques. For example, in one preferred embodiment, T cellsare isolated by incubation with anti-CD3/anti-CD28 (i.e.,3×28)-conjugated beads, such as DYNABEADS® M-450 CD3/CD28 T, or XCYTEDYNABEADS™ for a time period sufficient for positive selection of thedesired T cells. In one embodiment, the time period is about 30 minutes.In a further embodiment, the time period ranges from 30 minutes to 36hours or longer and all integer values there between. In a furtherembodiment, the time period is at least 1, 2, 3, 4, 5, or 6 hours. Inyet another preferred embodiment, the time period is 10 to 24 hours. Inone preferred embodiment, the incubation time period is 24 hours. Forisolation of T cells from patients with leukemia, use of longerincubation times, such as 24 hours, can increase cell yield. Longerincubation times may be used to isolate T cells in any situation wherethere are few T cells as compared to other cell types, such in isolatingtumor infiltrating lymphocytes (TIL) from tumor tissue or fromimmunocompromised individuals. Further, use of longer incubation timescan increase the efficiency of capture of CD8⁺ T cells.

Enrichment of a T cell population by negative selection can beaccomplished with a combination of antibodies directed to surfacemarkers unique to the negatively selected cells. A preferred method iscell sorting and/or selection via negative magnetic immunoadherence orflow cytometry that uses a cocktail of monoclonal antibodies directed tocell surface markers present on the cells negatively selected. Forexample, to enrich for CD4⁺ cells by negative selection, a monoclonalantibody cocktail typically includes antibodies to CD14, CD20, CD11b,CD16, HLA-DR, and CD8.

For isolation of a desired population of cells by positive or negativeselection, the concentration of cells and surface (e.g., particles suchas beads) can be varied. In certain embodiments, it may be desirable tosignificantly decrease the volume in which beads and cells are mixedtogether (i.e., increase the concentration of cells), to ensure maximumcontact of cells and beads. For example, in one embodiment, aconcentration of 2 billion cells/ml is used. In one embodiment, aconcentration of 1 billion cells/ml is used. In a further embodiment,greater than 100 million cells/ml is used. In a further embodiment, aconcentration of cells of 10, 15, 20, 25, 30, 35, 40, 45, or 50 millioncells/ml is used. In yet another embodiment, a concentration of cellsfrom 75, 80, 85, 90, 95, or 100 million cells/ml is used. In furtherembodiments, concentrations of 125 or 150 million cells/ml can be used.Using high concentrations can result in increased cell yield, cellactivation, and cell expansion. Further, use of high cell concentrationsallows more efficient capture of cells that may weakly express targetantigens of interest, such as CD28-negative T cells, or from sampleswhere there are many tumor cells present (i.e., leukemic blood, tumortissue, etc). Such populations of cells may have therapeutic value andwould be desirable to obtain. For example, using high concentration ofcells allows more efficient selection of CD8⁺ T cells that normally haveweaker CD28 expression.

In a related embodiment, it may be desirable to use lower concentrationsof cells. By significantly diluting the mixture of T cells and surface(e.g., particles such as beads), interactions between the particles andcells is minimized. This selects for cells that express high amounts ofdesired antigens to be bound to the particles. For example, CD4⁺ T cellsexpress higher levels of CD28 and are more efficiently captured thanCD8⁺ T cells in dilute concentrations. In one embodiment, theconcentration of cells used is 5×10⁶/ml. In other embodiments, theconcentration used can be from about 1×10⁵/ml to 1×10⁶/ml, and anyinteger value in between.

If desired or necessary, monocyte populations (i.e., CD14⁺ cells) may bedepleted from blood preparations prior to ex vivo expansion by a varietyof methodologies, including anti-CD14 coated beads or columns, orutilization of the phagocytotic activity of these cells to facilitateremoval. Accordingly, in one embodiment, the invention uses paramagneticparticles of a size sufficient to be engulfed by phagocytotic monocytes.In certain embodiments, the paramagnetic particles are commerciallyavailable beads, for example, those produced by Dynal AS under the tradename Dynabeads™. Exemplary Dynabeads™ in this regard are M-280, M-450,and M-500. In one aspect, other non-specific cells are removed bycoating the paramagnetic particles with “irrelevant” proteins (e.g.,serum proteins or antibodies). Irrelevant proteins and antibodiesinclude those proteins and antibodies or fragments thereof that do notspecifically target the T cells to be expanded. In certain embodimentsthe irrelevant beads include beads coated with sheep anti-mouseantibodies, goat anti-mouse antibodies, and human serum albumin.

In brief, such depletion of monocytes is performed by preincubating PBMCisolated from whole blood or apheresed peripheral blood with one or morevarieties of irrelevant or non-antibody coupled paramagnetic particlesat any amount that allows for removal of monocytes (approximately a 20:1bead:cell ratio) for about 30 minutes to 2 hours at 22 to 37 degrees C.,followed by magnetic removal of cells which have attached to or engulfedthe paramagnetic particles. Such separation can be performed usingstandard methods available in the art. For example, any magneticseparation methodology may be used including a variety of which arecommercially available, (e.g., DYNAL® Magnetic Particle Concentrator(DYNAL MPC®)). Assurance of requisite depletion can be monitored by avariety of methodologies known to those of ordinary skill in the art,including flow cytometric analysis of CD14 positive cells, before andafter said depletion.

T cells for stimulation can also be frozen after the washing step, whichdoes not require the monocyte-removal step. Wishing not to be bound bytheory, the freeze and subsequent thaw step provides a more uniformproduct by removing granulocytes and to some extent monocytes in thecell population. After the washing step that removes plasma andplatelets, the cells may be suspended in a freezing solution. While manyfreezing solutions and parameters are known in the art and will beuseful in this context, one method involves using PBS containing 20%DMSO and 8% human serum albumin, or other suitable cell freezing media,the cells then are frozen to −80° C. at a rate of 1° per minute andstored in the vapor phase of a liquid nitrogen storage tank. Othermethods of controlled freezing may be used as well as uncontrolledfreezing immediately at −20° C. or in liquid nitrogen.

T cells for use in the present invention may also be antigen-specific Tcells. For example, tumor-specific T cells can be used. In certainembodiments, antigen-specific T cells can be isolated from a patient ofinterest, such as a patient afflicted with a cancer or an infectiousdisease as described herein. In certain embodiments, antigen-specific Tcells can be induced by vaccination of a patient with a particularantigen, either alone or in conjunction with an adjuvant or pulsed ondendritic cells. Antigen-specific cells for use in expansion using theEMSP of the present invention may also be generated in vitro using anynumber of methods known in the art, for example, as described in U.S.Patent Application No. 60/469,122 entitled, GENERATION AND ISOLATION OFANTIGEN-SPECIFIC T CELLS, filed May 8, 2003, or in U.S. Pat. Nos.6,040,177 and 5,872,642. Antigen-specific cells for use in the presentinvention may also be generated using any number of methods known in theart, for example, as described in Current Protocols in Immunology, orCurrent Protocols in Cell Biology, both published by John Wiley & Sons,Inc., Boston, Mass.

In a related embodiment, it may be desirable to sort or otherwisepositively select (e.g. via magnetic selection) the antigen specificcells prior to or following one or two rounds of expansion with EMSPSorting or positively selecting antigen-specific cells can be carriedout using peptide-MHC tetramers (Altman, et al., Science. 1996 Oct. 4;274(5284):94-6.). In one embodiment antigen-specific T cells areisolated by contacting said T cells with antibodies specific for T cellactivation markers. Antibodies that can be used with the methods of thepresent invention include, but are not limited to, anti-CD25, anti-CD54,anti-CD69, anti-CD38, anti-CD45RO, anti-CD49d, anti-CD40L, anti-CD137,anti-IFN-γ, IL-2, IL-4, and other activation induced cytokines, andanti-CD134 antibodies. Sorting of antigen-specific T cells, or generallyany cells of the present invention, can be carried out using any of avariety of commercially available cell sorters, including, but notlimited to, MoFlo sorter (DakoCytomation, Fort Collins, Colo.),FACSAria™, FACSArray™, FACSVantage™, BD™ LSR II, and FACSCalibur™ (BDBiosciences, San Jose, Calif.).

Peptide-MHC tetramers can be generated using techniques known in the artand can be made with any MHC molecule of interest and any antigen ofinterest as described herein. Illustrative antigens that can be usedinclude but are not limited to, melanoma antigen Melan-A (also referredto as melanoma antigen recognized by T cells or MART-1), melanomaantigen-encoding genes 1, 2, and 3 (MAGE-1, -2, -3), melanoma GP100,carcinoembryonic antigen (CEA), the breast cancer antigen, Her-2/Neu,telomerase reverse transcriptase (hTERT), serum prostate specificantigen (PSA), Wilm's Tumor (WT-1), mucin antigens, MUC-1, -2, -3, -4,and B cell lymphoma idiotypes. Specific epitopes to be used in thiscontext can be identified using numerous assays known in the art. Forexample, the ability of a polypeptide to bind to MHC class I may beevaluated indirectly by monitoring the ability to promote incorporationof ¹²⁵I labeled β2-microglobulin (β2m) into MHC class I/β2 m/peptideheterotrimeric complexes (see Parker et al., J. Immunol. 152:163, 1994).

Further, antigenic epitopes for use in the present invention maygenerally be identified using well known techniques, such as thosesummarized in Paul, Fundamental Immunology, 3rd ed., 243-247 (RavenPress, 1993) and references cited therein. Representative techniques foridentifying epitopes include screening polypeptides for the ability toreact with antigen-specific T cell lines or clones. Such screens maygenerally be performed using methods well known to those of ordinaryskill in the art, such as those described in Harlow and Lane,Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988.Epitopes may also be identified using computer analysis, such as theTsites program (see Rothbard and Taylor, EMBO J 7:93-100, 1988; Deavinet al., Mol. Immunol. 33:145-155, 1996), which searches for peptidemotifs that have the potential to elicit T helper responses. CTLepitopes with motifs appropriate for binding to human class I or classII MHC may be identified according to BIMAS (Parker et al., J. Immunol.152:163, 1994) and other HLA peptide binding prediction analyses. Toconfirm peptide binding to human class I or class II MHC molecules,peptide binding assays known in the art may be used. To confirmimmunogenicity, a peptide may be tested using an HLA A2 or othertransgenic mouse model and/or an in vitro stimulation assay usingdendritic cells, fibroblasts or peripheral blood cells.

Stimulation of a Cell Population

As noted above, the present invention provides compositions and methodsfor stimulating a cell population by binding moieties on the surfaces ofthe cells in that population. Contacting a cell population with an agent(e.g., a ligand) that binds to a cell surface moiety can stimulate thecell population. The ligand may be in solution but also may be attachedto a surface. Ligation of cell surface moieties, such as a receptor, maygenerally induce a particular signaling pathway. Recent studies suggestthat for signaling to occur, critical concentrations of lipid raftscontaining the requisite receptors must aggregate. By way of example,raft aggregation may be facilitated in vivo or in vitro by attachingligands for particular cell surface moieties to an EMSP and exposing theligand-bearing EMSP to the cells of interest.

The methods of the present invention relate to the stimulation of atarget cell by introducing a ligand or agent that binds to a cellularmoiety, thereby inducing a cellular event. Binding of the ligand oragent to the cell may trigger a signaling pathway that in turn activatesparticular phenotypic or biological changes in the cell. The stimulationof a target cell by introducing a ligand or agent that binds to acellular moiety as described herein may upregulate or downregulate anynumber of cellular processes leading to particular phenotypic orbiological changes in the cell. The activation of the cell may enhancenormal cellular functions or initiate normal cell functions in anabnormal cell. The method described herein provides stimulation bycontacting the cells with the ligand or agent that binds a cell surfacemoiety. Stimulation of a cell may be enhanced or a particular cellularevent may be stimulated by introducing a second agent or ligand thatligates a second cell surface moiety. This method may be applied to anycell for which ligation of a cell surface moiety leads to a signalingevent. The invention further provides means for selection or culturingthe stimulated cells. The prototypic example described is stimulation ofT cells, but one of ordinary skill in the art will readily appreciatethat the method may be applied to other cell types. By way of example,cell types that may be stimulated and selected include fibroblasts,neuroblasts, lung cells, hematopoietic stem cells and hematopoieticprogenitor cells (CD34⁺ cells), mesenchymal stem cells, mesenchymalprogenitor cells, neural and hepatic progenitor and stem cells,dendritic cells, cytolytic T cells (CD8⁺ cells), T helper cells (CD4⁺cells), B-cells, NK cells, other leukocyte populations, pluripotent stemcells, multi-potent stem cells, islet cells, etc. Accordingly, thepresent invention also provides populations of cells resulting from thismethodology as well as cell populations having distinct phenotypicalcharacteristics, including T cells with specific phenotypiccharacteristics.

As noted above a variety of cell types may be utilized within thecontext of the present invention. For example, cell types such as Bcells, T cells, NK cells, other blood cells, neuronal cells, lung cells,glandular (endocrine) cells, bone forming cells (osteoclasts, etc.),germ cells (e.g., oocytes), epithelial cells lining reproductive organs,and others may be utilized. Cell surface moiety-ligand pairs couldinclude (but not exclusively): T cell antigen receptor (TCR) andanti-CD3 mAb, TCR and major histocompatibility complex (MHC)+antigen,TCR and peptide-MHC tetramer, TCR and superantigens (e.g.,staphylococcal enterotoxin B (SEB), toxic shock syndrome toxin (TSST),etc.), B cell antigen receptor (BCR) and anti-Ig, BCR and LPS, BCR andspecific antigens (univalent or polyvalent), NK receptor and anti-NKreceptor antibodies, FAS (CD95) receptor and FAS ligand, FAS receptorand anti-FAS antibodies, CD54 and anti-CD54 antibodies, CD2 and anti-CD2antibodies, CD2 and LFA-3 (lymphocyte function related antigen-3),cytokine receptors and their respective cytokines, cytokine receptorsand anti-cytokine receptor antibodies, TNF-R (tumor necrosisfactor-receptor) family members and antibodies directed against them,TNF-R family members and their respective ligands, adhesion/homingreceptors and their ligands, adhesion/homing receptors and antibodiesagainst them, oocyte or fertilized oocyte receptors and their ligands,oocyte or fertilized oocyte receptors and antibodies against them,receptors on the endometrial lining of uterus and their ligands, hormonereceptors and their respective hormone, hormone receptors and antibodiesdirected against them, and others.

The nature of the binding of a multivalent or monovalent receptor by aligand will either result in the multimerization of the receptors, oraggregation/orientation of the receptors, such that signaling or cellresponse is upregulated, down-regulated, accelerated, improved, orotherwise altered so as to confer a particular benefit, such as celldivision, cytokine secretion, cell migration, increased cell-cellinteraction, etc.

Two examples are given below that illustrate how such a multimerization,aggregation, or controlled reorientation of cell surface moieties couldbe of practical benefit.

In one example, normal T cell activation by antigen and antigenpresenting cells usually results in aggregation of TCR rafts,cytoskeletal reorganization, polarization of “activation” signals andcell division, for example. Using man-made approaches, such as thosedescribed herein, in the absence of “normal” in-vivo T cell activation,one could accelerate, improve, or otherwise affect the functionsdescribed above, in particular through the accelerated, controlled, andspatially oriented ligation of TCR and CD28 or 4-1BB or otherco-stimulatory molecules. Benefits include improved cell expansion invitro resulting in higher numbers of infuseable and more robust cellsfor therapeutic applications. Other benefits could be improved receptor“aggregation” for cells with defects, such as lower-than-normal TCRdensity on the cell surface. Similarly, in vivo applications could bebeneficial where specific T cell populations need to be activated, suchas tumor-specific T cells at tumor sites. Improved receptor aggregationand orientation could provide an activation signal otherwise difficultto obtain for functionally tolerized T cells. Within this and othercontexts of the present invention, the EMSP can be used to breaktolerance against tumor antigens, autoantigens, or other pathogenicantigens such as viral antigens. Further, such activation could be usedwithin the context of antigen specific T cells. In this regard T cellsfrom a tumor could be isolated and expanded and infused into thepatient. Similarly, T cells exposed to an antigen either in vivo or invitro could be expanded by the present methodologies.

In one particular embodiment of the invention, a T cell population maybe stimulated by ligating the surfaces of the T cells. In one aspect ofthe present invention, antibodies to CD3 and CD28 are loaded onto anEMSP. In another aspect of the present invention, any ligand that bindsthe TCR/CD3 complex and initiates a primary stimulation signal may beutilized as a primary activation agent loaded onto or expressed by theEMSP. Any ligand that binds CD28 and initiates the CD28 signaltransduction pathway, thus causing co-stimulation of the cell with a CD3ligand and enhancing activation of a population of T cells, is a CD28ligand and accordingly, is a co-stimulatory agent within the context ofthe present invention.

In other aspects of the present invention, T cells can be exposed to abead conjugated agent or soluble forms of agents or ligands prior to orconcurrently with the EMSPs of the present invention as describedherein.

In certain embodiments, the EMSP of the present invention can becontacted with paramagnetic particles such that said paramagneticparticles are engulfed by the EMSP. EMSP comprising paramagneticparticles can then be subjected to magnetic force and concentrated orlocalized to a particular site of interest, such as a tumor, site ofviral infection or site of autoimmune disease, and/or otherwiseselected, either in vitro or in vivo.

In certain embodiments the EMSP of the present invention can becontacted with synthesized or magnetic liposomes or derivatizedbiodegradable glass.

The Primary Signal

The biochemical events responsible for ex vivo T cell stimulation areset forth briefly below. Interaction between the TCR/CD3 complex andantigen presented in conjunction with either MHC class I or class IImolecules on an antigen-presenting cell initiates a series ofbiochemical events termed antigen-specific T cell activation.Accordingly, activation of T cells can be accomplished by stimulatingthe T cell TCR/CD3 complex or by stimulating the CD2 surface protein. Ananti-CD3 monoclonal antibody can be used to activate a population of Tcells via the TCR/CD3 complex. A number of anti-human CD3 monoclonalantibodies are commercially available, exemplary are OKT3, prepared fromhybridoma cells obtained from the American Type Culture Collection, andmonoclonal antibody G19-4. Similarly, stimulatory forms of anti-CD2antibodies are known and available. Stimulation through CD2 withanti-CD2 antibodies is typically accomplished using a combination of atleast two different anti-CD2 antibodies. Stimulatory combinations ofanti-CD2 antibodies that have been described include the following: theT11.3 antibody in combination with the T11.1 or T11.2 antibody (Meuer etal., Cell 36:897-906, 1984), and the 9.6 antibody (which recognizes thesame epitope as T11.1) in combination with the 9-1 antibody (Yang etal., J. Immunol. 137:1097-1100, 1986). Other antibodies that bind to thesame epitopes as any of the above described antibodies can also be used.Additional antibodies, or combinations of antibodies, can be preparedand identified by standard techniques.

A primary activation signal can also be delivered to a T cell throughother mechanisms. For example, a combination that may be used includes aprotein kinase C (PKC) activator, such as a phorbol ester (e.g., phorbolmyristate acetate), and a calcium ionophore (e.g., ionomycin, whichraises cytoplasmic calcium concentrations), or the like. The use of suchagents bypasses the TCR/CD3 complex but delivers a stimulatory signal toT cells. Other agents acting as primary signals may include natural andsynthetic ligands. A natural ligand may include MHC with or without apeptide presented. Other ligands may include, but are not limited to, apeptide, polypeptide, growth factor, cytokine, chemokine, glycopeptide,soluble receptor, steroid, hormone, mitogen, such as PHA, or othersuperantigens, peptide-MHC tetramers (Altman, et al., Science. 1996 Oct.4; 274(5284):94-6.) and soluble MHC dimers (Dal Porto, et al., Proc NatlAcad Sci USA 1993 Jul. 15; 90). Within the context of the presentinvention, the use of the EMSP for stimulation may result in stimulationsuch that no secondary signal is required to induce proliferation of Tcells.

In other embodiments, signal transduction events of any kind may bemagnified or analyzed by utilizing the current invention. For example, Gprotein-coupled receptors may stimulated and measured using the methodsof the present invention.

The Secondary Signal

While stimulation of the TCR/CD3 complex or CD2 molecule appears to berequired for delivery of a primary activation signal in a T cell, anumber of molecules on the surface of T cells, termed accessory orco-stimulatory molecules, have been implicated in regulating thetransition of a resting T cell to blast transformation, and subsequentproliferation and differentiation. Thus, in addition to the primaryactivation signal, induction of T cell responses requires a second,co-stimulatory signal. One such co-stimulatory or accessory molecule,CD28, is believed to initiate or regulate a signal transduction pathwaythat is distinct from any stimulated by the TCR complex. Another suchco-stimulatory or, accessory molecule, 4-1BB, preferentially stimulatesCD8⁺ T cells but may also be used for the stimulation of CD4⁺ T cells.

Therefore, to enhance activation and proliferation of a population of Tcells in the absence of exogenous growth factors or accessory cells, anaccessory molecule on the surface of the T cell, such as CD28 or 4-1BB,is stimulated with a ligand that binds the accessory molecule. In oneembodiment, stimulation of the accessory molecule CD28 and T cellactivation occur simultaneously by contacting a population of T cellswith an EMSP to which a ligand that binds CD3 and a ligand that bindsCD28 are attached. In another embodiment, stimulation of the accessorymolecule 4-1BB and T cell activation occur simultaneously by contactinga population of T cells with an EMSP to which a ligand that binds CD3and a ligand that binds 4-1BB are attached. Activation of the T cells,for example, with an anti-CD3 antibody, and stimulation of the CD28accessory molecule results in selective proliferation of CD4⁺ T cells.Activation of the T cells, for example, with an anti-CD3 antibody, andstimulation of the 4-1BB accessory molecule results in preferentialproliferation of CD8⁺ T cells.

Accordingly, one of ordinary skill in the art will recognize that anyagent, including an anti-CD28 antibody or fragment thereof capable ofcross-linking the CD28 molecule, or a natural ligand for CD28 can beused to stimulate T cells. Exemplary anti-CD28 antibodies or fragmentsthereof useful in the context of the present invention includemonoclonal antibody 9.3 (IgG2_(a)) (Bristol-Myers Squibb, Princeton,N.J.), monoclonal antibody KOLT-2 (IgG1), 15E8 (IgG1), 248.23.2 (IgM),and EX5.3D10 (IgG2_(a)) (ATCC HB11373). Exemplary natural ligandsinclude the B7 family of proteins, such as B7-1 (CD80) and B7-2 (CD86)(Freedman et al., J. Immunol. 137:3260-3267, 1987; Freeman et al., J.Immunol. 143:2714-2722, 1989; Freeman et al., J. Exp. Med. 174:625-631,1991; Freeman et al., Science 262:909-911, 1993; Azuma et al., Nature366:76-79, 1993; Freeman et al., J. Exp. Med. 178:2185-2192, 1993). Inaddition, binding homologues of a natural ligand, whether native orsynthesized by chemical or recombinant techniques, can also be used inaccordance with the present invention. Other agents acting as secondarysignals may include natural and synthetic ligands. Agents may include,but are not limited to, other antibodies or fragments thereof, apeptide, polypeptide, growth factor, cytokine, chemokine, glycopeptide,soluble receptor, steroid, hormone, mitogen, such as PHA, or othersuperantigens.

Likewise, one of ordinary skill in the art will recognize that anyagent, including an anti-4-1BB antibody or fragment thereof capable ofcross-linking the 4-1BB molecule, or a natural ligand for 4-1BB can beused to stimulate T cells. In particular, human 4-1 BB ligand can becloned from B cells into the pcDNA3, or other suitable vectors and betransfected into an EMSP.

In a further embodiment of the invention, activation of a T cellpopulation may be enhanced by co-stimulation of other T cell integralmembrane proteins. For example, binding of the T cell integrin LFA-1 toits natural ligand, ICAM-1, may enhance activation of cells. Anothercell surface molecule that may act as a co-stimulator for T cells isVCAM-1 (CD106) that binds very-late-antigen-4 (VLA-4) on T cells.

In certain embodiments of the present invention, stimulation,activation, and expansion of T cells using EMSP as described hereinenhances expression of certain key molecules in T cells that protectagain apoptosis or otherwise prolong survival in vivo or in vitro.Apoptosis usually results from induction of a specific signal in the Tcell. Thus, the compositions and methods of the invention provide forprotecting a T cell from cell death resulting from stimulation of the Tcell. It is known in the art that presently cross-linking of the T cellreceptor, either by a polyclonal activator, such as an anti-CD3 antibodyand/or anti-CD28 antibody, or alternatively by an antigen on an antigenpresenting cell (APC), in the absence of a co-stimulatory signal, canresult in T cell anergy or T cell death. Therefore, also included in thepresent invention is the enhanced T cell growth by protection frompremature death or from absence or depletion of recognized T cell growthmarkers, such as Bcl-xL, growth factors, cytokines, or lymphokinesnormally necessary for T cell survival, as well as from Fas or TumorNecrosis Factor Receptor (TNFR) cross-linking or by exposure to certainhormones or stress.

One of skill in the art will appreciate that cells other than T cellsmay be stimulated by binding of an agent that ligates a cell surfacemoiety and induces aggregation of the moiety, which in turn results inactivation of a signaling pathway. Other such cell surface moietiesinclude, but are not limited to, GPI-anchored folate receptor (CD59),human IgE receptor (FcεRi receptor), BCR, EGF receptor, insulinreceptor, ephrin B 1 receptor, neurotrophin, glial-cell derivedneutrophic factor (GNDF), hedgehog and other cholesterol-linked andpalmitoylated proteins, H-Ras, integrins, endothelial nitric oxidesynthase (eNOS), FAS, members of the TNF receptor family, GPI-anchoredproteins, doubly acylated proteins, such as the Src-family kinases, thealpha-subunit of heterotrimeric G proteins, and cytoskeletal proteins.

The cell population may be stimulated as described herein, such as bycontact with an anti-CD3 antibody or an anti-CD2 antibody loaded onto anEMSP engineered to express an Fcγ receptor such as CD32, or by contactwith a protein kinase C activator (e.g., bryostatin) in conjunction witha calcium ionophore. For co-stimulation of an accessory molecule on thesurface of the T cells, a ligand that binds the accessory molecule isused. For example, a population of CD4⁺ cells can be contacted with ananti-CD3 antibody and an anti-CD28 antibody, under conditionsappropriate for stimulating proliferation of the T cells. Similarly, tostimulate proliferation of CD8⁺ T cells, an anti-CD3 antibody and the4-1BB ligand can be used. Alternatively, to stimulate proliferation ofCD8⁺ T cells, an anti-CD3 antibody and the anti-CD28 antibody B-T3,XR-CD28 (Diaclone, Besançon, France) can be used as can other methodscommonly known in the art (Berg et al., Transplant Proc.30(8):3975-3977, 1998; Haanen et al., J. Exp. Med. 190(9):1319-1328,1999; Garland et al., J. Immunol Meth. 227(1-2):53-63, 1999).

The primary stimulatory signal and the co-stimulatory signal for the Tcell may be provided by different protocols. For example, the agentsproviding each signal may be in solution or coupled to a surface such asloaded on an EMSP as described herein. When loaded on an EMSP or othersurface, such as a paramagnetic bead, the agents may be loaded on thesame EMSP or coupled to the same surface (i.e., in “cis” formation) orcan be loaded onto separate EMSP or coupled to separate surfaces (i.e.,in “trans” formation). Alternatively, one agent may be loaded on an EMSPor coupled to a surface and the other agent in solution. In oneembodiment, the agent providing the co-stimulatory signal is bound to acell surface and the agent providing the primary activation signal is insolution or coupled to a surface. In certain embodiments, both agentscan be in solution. In another embodiment, the agents may be in solubleform, and then bound to a surface, such as a cell expressing Fcreceptors or an antibody or other binding agent which will bind to theagents. In a preferred embodiment, the two agents are loaded onto thesame EMSP that has been engineered to express an FCγ receptor such asCD32. By way of example, the agent providing the primary activationsignal is an anti-CD3 antibody and the agent providing theco-stimulatory signal is an anti-CD28 antibody; and both agents areloaded onto an EMSP in equivalent molecular amounts. In one embodiment,a 1:1 ratio of each antibody loaded onto an EMSP for CD4⁺ T cellexpansion and T cell growth is used. In certain aspects of the presentinvention, a ratio of anti CD3:CD28 antibodies loaded onto an EMSP isused such that an increase in T cell expansion is observed as comparedto the expansion observed using a ratio of 1:1. In one particularembodiment an increase of from about 0.5 to about 3 fold is observed ascompared to the expansion observed using a ratio of 1:1. In oneembodiment, the ratio of CD3:CD28 antibody loaded onto an EMSP rangesfrom 100:1 to 1:1000 and all integer values there between. In one aspectof the present invention, more anti-CD28 antibody is loaded onto an EMSPthan anti-CD3 antibody, i.e. the ratio of CD3:CD28 is less than one. Incertain embodiments of the invention, the ratio of anti CD28 antibody toanti CD3 antibody loaded onto an EMSP is greater than 2:1. In oneparticular embodiment, a 1:1000 CD3:CD28 ratio of antibody loaded ontoan EMSP is used. In another embodiment, a 1:500 CD3:CD28 ratio ofantibody loaded onto an EMSP is used. In another embodiment, a 1:250CD3:CD28 ratio of antibody loaded onto an EMSP is used. In anotherembodiment, a 1:100 CD3:CD28 ratio of antibody loaded onto an EMSP isused. In a further embodiment, a 1:75 or 1:50 CD3:CD28 ratio of antibodyloaded onto an EMSP is used. In another embodiment, a 1:40 or 1:30CD3:CD28 ratio of antibody loaded onto an EMSP is used. In one preferredembodiment, a 1:100 CD3:CD28 ratio of antibody loaded onto an EMSP isused. In another preferred embodiment, a 1:50 CD3:CD28 ratio of antibodyloaded onto an EMSP is used. In another preferred embodiment, a 1:25CD3:CD28 ratio of antibody loaded onto an EMSP is used. In one preferredembodiment, a 1:10 CD3:CD28 ratio of antibody loaded onto an EMSP isused. In another embodiment, a 1:3 CD3:CD28 ratio of antibody loadedonto an EMSP is used. In yet another embodiment, a 3:1 CD3:CD28 ratio ofantibody loaded onto an EMSP is used.

Ratios of EMSP, or other particles as described herein, to cells from1:10000 to 10000:1 and any integer values in between may be used tostimulate T cells or other target cells. As those of ordinary skill inthe art can readily appreciate, the ratio of EMSP to cells may dependanton EMSP size relative to the target cell. For example, a small EMSPcould only bind a few cells, while a large EMSP could bind many. Incertain embodiments the ratio of cells to EMSP ranges from 1:100 to100:1 and any integer values in-between and in further embodiments theratio comprises 1:9, 1:8, 1:7, to 9:1 and any integer values in between,can also be used to stimulate T cells. In a preferred embodiment whereinthe EMSP is K32 as described herein in the Examples, the ratio of targetcell to EMSP is most suitable at about 1:1 to about 1:100. The ratio ofanti-CD3- and anti-CD28-loaded EMSP to T cells that result in T cellstimulation can vary as noted above, however certain preferred valuesinclude at least 1:200, 1:150, 1:100, 1:75, 1:50, 1:45, 1:40, 1:35,1:30, 1:25, 1:20, 1:15, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2.5,1:2, 1:1.5, 1:1, 2:1, 3:1, 4:1 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1,20:1, to 25:1, with one preferred ratio being at least 1:1 EMSP per Tcell. In one embodiment, a ratio of EMSP to cells of 1:1 or less isused.

Using different EMSP:cell ratios can lead to different outcomes withrespect to expansion of antigen-specific T cells, as described forexample in U.S. Patent Application No. 60/469,122, filed May 8, 2003. Inparticular, EMSP:cell ratios can be varied to selectively expand ordelete antigen-specific (memory) T cells. In one embodiment, theparticular EMSP:cell ratio used selectively deletes antigen-specific Tcells. In a further embodiment, the particular EMSP:cell ratio usedselectively expands antigen-specific T cells. For example, EMSP to cellratios of 1:100, 1:50, 1:25, 1:5 or 1:2.5 and the like are used toexpand antigen-specific T cells. Low EMSP:cell ratio can help preserveand promote expansion of memory (antigen-specific) T cells.Additionally, when additional EMSPs are added at very low ratios (1:10,1:25, 1:50, 1:100) at various days of culture (e.g. day 5, 7, or 9), onecan enhance and even promote preferential expansion of the memory cells.With either 1:5 or 1:2.5 EMSP:cell ratio as initial stimulus, additionof 1:10, 1:25, and to some extent 1:50 and 1:100 EMSP:cell ratio at days5 and 7 may preserve and enhance further expansion of memory cells thatwould otherwise not occur with a single stimulation at day 0. Therefore,the compositions and methods described herein can be used to expandspecific populations of T cells, or to delete specific populations of Tcells, for use in any variety of immunotherapeutic settings describedherein.

Using certain methodologies it may be advantageous to maintain long-termculture of a population of T cells following the initial activation andstimulation, by separating the T cells from the stimulus after a periodof about 12 to about 14 days. In certain embodiments, it may bedesirable to separate the T cells from the stimulus after a period ofabout 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 days. In certain embodiments, itmay be desirable to separate the T cells from the stimulus after aperiod of less than one day, such as after about an hour, or 2, 3, 4, 5,6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23hours. The rate of T cell proliferation is monitored periodically (e.g.,daily) by, for example, examining the size or measuring the volume ofthe T cells, such as with a Coulter Counter. In this regard, a resting Tcell has a mean diameter of about 6.8 microns, and upon initialactivation and stimulation, in the presence of the stimulating ligand,the T cell mean diameter will increase to over 12 microns by day 4 andbegin to decrease by about day 6. When the mean T cell diameterdecreases to approximately 8 microns, the T cells may be reactivated andre-stimulated to induce further proliferation of the T cells.Alternatively, the rate of T cell proliferation and time for T cellre-stimulation can be monitored by assaying for the presence of cellsurface molecules, such as, CD154, CD54, CD25, CD137, CD134, which areinduced on activated T cells. Intracellular or secreted cytokines canalso be monitored such as IL-2, IFN-γ, TNF-α, GM-CSF, etc.

In further embodiments of the present invention, the cells, such as Tcells, are combined with loaded EMSP, the EMSP and the cells aresubsequently separated, and then the cells are cultured. In analternative embodiment, prior to culture, the antibody or ligand loadedEMSP and cells are not separated but are cultured together.

By way of example, when T cells are the target cell population, the cellsurface moieties may be ligated by allowing irradiated EMSP expressingCD86 and to which anti-CD3 and anti-CD28 are attached via the Fcγreceptor to contact the T cells. In another example of the presentinvention, when T cells are the target cell population, the cell surfacemoieties may be ligated by allowing irradiated EMSP expressing the 4-1BBligand and to which anti-CD3 and anti-CD28 are attached via the Fcγreceptor to contact the T cells.

The buffer that the cells are suspended in may be any that isappropriate for the particular cell type. When utilizing certain celltypes the buffer may contain other components, e.g., 1-5% serum,necessary to maintain cell integrity during the process. In anotherembodiment, the cells and EMSP may be combined in cell culture media.The cells and EMSP may be mixed, for example, by rotation, agitation orany means for mixing, for a period of time ranging from one minute toseveral hours. As noted above, generally the EMSP of the presentinvention are irradiated prior to contact with target cells such as Tcells. Generally, EMSP are irradiated prior to being loaded withantibodies or ligands as described herein.

In one embodiment of the present invention, the mixture may be culturedfor several hours (about 3 hours) to about 20 days or any hourly integervalue in between. In another embodiment, the mixture may be cultured for21 days. In one embodiment of the invention the EMSP and the T cells arecultured together for about eight days. In another embodiment, the EMSPand T cells are cultured together for 2-3 days. Several cycles ofstimulation may also be desired such that culture time of T cells can be60 days or more.

The period of initial stimulation or restimulation as described herein(contact with agents as described herein) can be very short, for exampleless than 24 hours such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 21, 22, or 23 hours. The period of initialstimulation or restimulation as described further herein (contact withagents as described herein) can be longer, for example 1, 2, 3, 4, 5, 6,7, 8, 9, 10 or more days.

Conditions appropriate for T cell culture include an appropriate media(e.g., Minimal Essential Media or RPMI Media 1640 or, X-vivo 15,(BioWhittaker)) that may contain factors necessary for proliferation andviability, including serum (e.g., fetal bovine or human serum),interleukin-2 (IL-2), insulin, IFN-γ, IL-4, GM-CSF, IL-10, IL-12, TGFβ,and TNF-α or any other additives for the growth of cells known to theskilled artisan. Other additives for the growth of cells include, butare not limited to, surfactant, plasmanate, and reducing agents such asN-acetyl-cysteine and 2-mercaptoethanol. Media can include RPMI 1640,AIM-V, DMEM, MEM, α-MEM, F-12, X-Vivo 15, and X-Vivo 20, with addedamino acids and vitamins, either serum-free or supplemented with anappropriate amount of serum (or plasma) or a defined set of hormones,and/or an amount of cytokine(s) sufficient for the growth and expansionof T cells. Antibiotics, e.g., penicillin and streptomycin, are includedonly in experimental cultures, and preferably n\not in cultures of cellsthat are to be infused into a subject. The target cells are maintainedunder conditions necessary to support growth, for example, anappropriate temperature (e.g., 37° C.) and atmosphere (e.g., air plus 5%CO₂).

Cells stimulated by the methods of the present invention are activatedas shown by the induction of signal transduction, expression of cellsurface markers and/or proliferation. One such marker appropriate for Tcells is CD154 which is an important immunomodulating molecule. Theexpression of CD154 is extremely beneficial in amplifying the immuneresponse. CD154 interacts with the CD40 molecule expressed on many Bcells, dendritic cells, monocytes, and some endothelial cells.Accordingly, this unexpected and surprising increase in CD154 expressionis likely to lead to more efficacious T cell compositions. Stimulationof CD3⁺ cells as described herein provides T cells that express a 1.1 to20-fold increases in the levels of certain cell surface markers such asCD154 expression on days 1, 2, 3, or 4 following stimulation. Expressionof another cell surface marker, CD25, also was greater on T cells afterstimulation than on cells prior to culture or cells stimulated by othermethods. Further, after simulation using the methods of the presentinvention, CD8⁺ T cells show increased Bcl-xL and IL-2 expression asdescribed in the Examples below.

In another embodiment, T cells are initially stimulated with the EMSPand the T cells are then purified using any number of methods describedherein, also including density gradient separation, elutriation andremoval of dead cells. The remaining T cell population is substantiallyfree of non-T cells and can then be incubated with any number ofcytokines such as IL-2 in culture medium in order to promote further Tcell proliferation.

One of skill in the art will appreciate that any target cell that can bestimulated by cell surface moiety ligation may be combined with theEMSP. Further, the EMSP may be separated from the cells prior toculture, at any point during culture, or at the termination of culture.In addition, the EMSP ligated to the target cells may be separated fromthe non-binding cells prior to culture or the other cells may remain inculture as well. In one embodiment, prior to culture, the EMSP andtarget cells are not separated but are cultured together.

Also contemplated by this invention, are means to increase theconcentration of the target cells, for example, a T cell fraction boundto an EMSP coated with primary and secondary stimulatory molecules. Forexample, forces greater than gravitational force may be applied, forexample, but not limited to, centrifugal force, transmembrane pressure,and a hydraulic force. Concentration may also be accomplished byfiltration. In certain embodiments, the EMSP of the present inventioncan be contacted with paramagnetic particles, such as paramagnetic beadsor magnetic liposomes, such that said paramagnetic particles areengulfed by the EMSP. EMSP comprising paramagnetic particles can then besubjected to magnetic force and concentrated and/or otherwise selected,either in vitro or in vivo.

One of skill in the art will readily appreciate that contact between theagent-coated or otherwise loaded EMSP and the cells to be stimulated canbe increased by concentration using other forces. Accordingly, any meansfor concentrating cells with cell surface moiety binding ligands will besufficient as long as the concentration brings together cells and agentsin a manner that exceeds gravity or diffusion.

A cellular event induced by contact of target cells with the EMSP of thepresent invention may include, for example, receptor-mediated signaltransduction that induces or suppresses a particular pathway, includingan apoptotic pathway, or induces phosphorylation of proteins, orstimulates or suppresses growth signals.

In another embodiment, the time of exposure to stimulatory agents suchas anti-CD3/anti-CD28-coated or otherwise loaded EMSP expressing CD86 or4-1BB may be modified or tailored to obtain a desired T cell phenotype.Alternatively, a desired population of T cells can be selected using anynumber of selection techniques, prior to stimulation. One may desire agreater population of CD4⁺ T cells as opposed to CD8⁺ or regulatory Tcells, because an expansion of CD4⁺ T cells could improve or restoreoverall immune responsiveness. While many specific immune responses aremediated by CD8⁺ antigen-specific T cells, which can directly lyse orkill undesired cells, most immune responses require the help of CD4⁺ Tcells, which express important immune-regulatory molecules, such asGM-CSF, CD40L, and IL-2, for example. Increased numbers of CD4⁺ T cellscan increase the amount of cell-expressed CD40L introduced intopatients, potentially improving target cell visibility (improved APCfunction). Similar effects can be seen by increasing the number ofinfused cells expressing GM-CSF, or IL-2, all of which are expressedpredominantly by CD4⁺ T cells. Alternatively, in situations whereCD4-help is needed less and increased numbers of CD8⁺ T cells aredesirous, the approaches described herein can also be utilized, by forexample, pre-selecting for CD8⁺ cells prior to stimulation and/orculture. Such situations may exist where increased levels of IFN-γ orincreased cytolysis of an undesired cell is preferred. In certain otherembodiments, selection of a CD28-negative population may be desired.

T cells that have been exposed to varied stimulation times and EMSPexpressing a variety of molecules may exhibit different characteristicsFor example, typical blood or apheresed peripheral blood mononuclearcell products have a CD4⁺ T cell population that is greater than thecytotoxic or suppressor T cell population (T_(C), CD8⁺). Ex vivoexpansion of T cells by stimulating CD3 and CD28 receptors produces apopulation of T cells that prior to about days 8-9 consistspredominately of T_(H) cells, while after about days 8-9, the populationof T cells comprises an increasingly greater population of T_(C) cells.Furthermore, one aspect of the present invention is the finding thatstimulation with an EMSP expressing 4-1BB ligand and coated withanti-CD3 and CD28 antibodies preferentially stimulates and expands CD8⁺cytotoxic T cells. Accordingly, depending on the purpose of treatment,infusing a subject with a T cell population comprising predominately ofT_(H) cells expanded with anti-CD3/anti-CD28 and CD86 EMSP may beadvantageous. Similarly, if an antigen-specific subset of T_(C) cellshas been isolated it may be beneficial to expand this subset to agreater degree using EMSP expressing 4-1BB and further coated withanti-CD3 and anti-CD28 antibodies.

Further, in addition to CD4 and CD8 markers, other phenotypic markersvary significantly, but in large part, reproducibly during the course ofthe cell expansion process. Thus, such reproducibility enables theability to tailor an activated T cell product for specific purposes.

In one such example, among the important phenotypic markers thatreproducibly vary with time are the high affinity IL-2 receptor (CD25),CD40 ligand (CD154), and CD45RO (a molecule that by preferentialassociation with the TCR may increase the sensitivity of the TCR toantigen binding). As one of ordinary skill in the art readilyappreciates, such molecules are important for a variety of reasons. Forexample, CD25 constitutes an important part of the autocrine loop thatallows rapid T cell division. CD154 has been shown to play a key role instimulating maturation of the antigen-presenting dendritic cells;activating B-cells for antibody production; regulating T_(H) cellproliferation; enhancing T_(C) cell differentiation; regulating cytokinesecretion of both T_(H) cells and antigen-presenting cells; andstimulating expression of co-stimulatory ligands, including CD80, CD86,and CD154.

Cytokine production peaks in the first few days of the ex vivo expansionprocess. Accordingly, because cytokines are known to be important formediating T cell activation and function as well as immune responsemodulation, such cytokines are likely critical in the development of atherapeutic T cell product, that is able to undergo reactivation uponcontact with an additional antigen challenge. Cytokines important inthis regard, include, but are not limited to, IL-2, IL-4, TNF-α, andIFN-γ. Thus, by obtaining a population of T cells during the first fewdays of expansion and infusing these cells into a subject, a therapeuticbenefit may occur in which additional activation and expansion of Tcells in vivo occurs.

In addition to the cytokines and the markers discussed previously,expression of adhesion molecules known to be important for mediation ofT cell activation and immune response modulation also changedramatically but reproducibly over the course of the ex vivo expansionprocess. For example, CD62L is important for homing of T cells tolymphoid tissues and trafficking T cells to sites of inflammation. Undercertain circumstances of disease and injury, the presence of activated Tcells at these sites may be disadvantageous. Because down-regulation ofCD62L occurs early following activation, the T cells could be expandedfor shorter periods of time. Conversely, longer periods of time inculture would generate a T cell population with higher levels of CD62Land thus a higher ability to target the activated T cells to these sitesunder other preferred conditions. Another example of a polypeptide whoseexpression varies over time is CD49d, an adhesion molecule that isinvolved in trafficking lymphocytes from blood to tissues spaces atsites of inflammation. Binding of the CD49d ligand to CD49d also allowsthe T cell to receive co-stimulatory signals for activation andproliferation through binding by VCAM-1 or fibronectin ligands. Theexpression of the adhesion molecule CD54, involved in T cell-APC and Tcell-T cell interactions as well as homing to sites of inflammation,also changes over the course of expansion. Accordingly, T cells could bestimulated for selected periods of time that coincide with the markerprofile of interest and subsequently collected and infused. Thus, T cellpopulations could be tailored to express the markers believed to providethe most therapeutic benefit for the indication to be treated.

Those of ordinary skill in the art will readily appreciate that the cellstimulation methodologies described herein may be carried out in avariety of environments (i.e., containers). For example, such containersmay be culture flasks, culture bags, or any container capable of holdingcells, preferably in a sterile environment. In one embodiment of thepresent invention a bioreactor is also useful. For example, severalmanufacturers currently make devices that can be used to grow cells andbe used in combination with the methods of the present invention. Seefor example, Celdyne Corp., Houston, Tex.; Unisyn Technologies,Hopkinton, Mass.; Synthecon, Inc. Houston, Tex.; Aastrom Biosciences,Inc. Ann Arbor, Mich.; Wave Biotech LLC, Bedminster, N.J. Further,patents covering such bioreactors include U.S. Pat. Nos. 6,096,532;5,985,653; 5,888,807; 5,190,878, which are incorporated herein byreference.

One aspect of the present invention provides stimulating and/oractivating or otherwise culturing cells in a rocking, closed system andresults in a profound enhancement in activation and expansion of thesecells. Accordingly, in one embodiment, a bioreactor with a base rockerplatform is used, for example such as “THE WAVE BIOREACTOR™” (WaveBiotech LLC, Bedminster, N.J.), that allows for varying rates of rockingand at a variety of different rocking angles. The skilled artisan willrecognize that any platform that allows for the appropriate motion foroptimal expansion of the cells is within the context of the presentinvention.

In certain embodiments, the capacity of the bioreactor container rangesfrom about 0.1 liter to about 200 liters of medium. The skilled artisanwill readily appreciate that the volume used for culture will varydepending on the number of starting cells and on the final number ofcells desired. In a related embodiment, the entire process ofstimulation, activation, and expansion takes place using staticconditions and/or in a bioreactor. Illustrative bioreactors include, butare not limited to, “THE WAVE BIOREACTOR™”.

In one particular embodiment, the cell stimulation methods of thepresent invention are carried out in a closed system, such as abioreactor, that allows for perfusion of medium at varying rates, suchas from about 0.1 ml/minute to about 3 ml/minute. Accordingly, incertain embodiments, the container of such a closed system comprises anoutlet filter, an inlet filter, and a sampling port for sterile transferto and from the closed system. In other embodiments, the container ofsuch a closed system comprises a syringe pump and control for steriletransfer to and from the closed system. Further embodiments provide fora mechanism, such as a load cell, for controlling media in-put andout-put by continuous monitoring of the weight of the bioreactorcontainer. In one embodiment the system comprises a gas manifold. Inanother embodiment, the bioreactor of the present invention comprises aCO₂ gas mix rack that supplies a mixture of ambient air and CO₂ and/orother gas mixes, to the bioreactor container and maintains the containerat positive pressure. In another embodiment, the bioreactor of thepresent invention comprises a variable heating element.

In one embodiment, media is allowed to enter the container starting onday 2, 3, 4, 5, or 6 at about 0.5 to 5.0 liters per day until thedesired final volume is achieved. In one preferred embodiment, mediaenters the container at 2 liters per day starting at day 4, until thevolume reaches 10 liters. Once desired volume is achieved, perfusion ofmedia can be initiated. In certain embodiments, perfusion of mediathrough the system is initiated on about day 2, 3, 4, 5, 6, 7, 8, 9, 10,11, or 12 of culture. In one embodiment, perfusion is initiated when thevolume is at about 0.1 liter to about 200 liters of media. In oneparticular embodiment, perfusion is initiated when the final volume isat 4, 5, 6, 7, 8, 9, 10, or 20 liters.

In a further embodiment of the present invention, the cells, such as Tcells, are cultured for up to 5 days in a closed, static system and thentransferred to a closed system that comprises a rocking element to allowrocking of the culture container at varying speeds.

Although the antibodies used in the methods described herein can bereadily obtained from public sources, such as the ATCC, antibodies to Tcell accessory molecules and the CD3 complex can be produced by standardtechniques. Methodologies for generating antibodies for use in themethods of the invention are well-known in the art and are discussed infurther detail herein.

Agents

Agents contemplated by the present invention include protein ligands,natural ligands, and synthetic ligands. Agents that can bind to cellsurface moieties, and under certain conditions, cause ligation andaggregation that leads to signaling include, but are not limited to,lectins (for example, PHA, lentil lectins, concanavalin A), antibodies,antibody fragments, peptides, polypeptides, glycopeptides, receptors, Bcell receptor and T cell receptor ligands, extracellular matrixcomponents, steroids, hormones (for example, growth hormone,corticosteroids, prostaglandins, tetra-iodo thyronine), bacterialmoieties (such as lipopolysaccharides), mitogens, antigens,superantigens and their derivatives, growth factors, cytokine, viralproteins (for example, HIV gp-120), adhesion molecules (such as,L-selectin, LFA-3, CD54, LFA-1), chemokines, and small molecules. Theagents may be isolated from natural sources such as cells, bloodproducts, and tissues, or isolated from cells propagated in vitro, orprepared recombinantly, or by other methods known to those with skill inthe art.

In one aspect of the present invention, when it is desirous to stimulateT cells, useful agents include ligands that are capable of binding theCD3/TCR complex, CD2, and/or CD28, and/or 4-1BB and initiatingactivation or proliferation, respectively. Accordingly, the term ligandincludes those proteins that are the “natural” ligand for the cellsurface protein, such as a B7 molecule for CD28, as well as artificialligands such as antibodies directed to the cell surface protein orfusions of antibodies or other ligands. Such antibodies and fragmentsthereof may be produced in accordance with conventional techniques, suchas hybridoma methods and recombinant DNA and protein expressiontechniques. Useful antibodies and fragments may be derived from anyspecies, including humans, or may be formed as chimeric proteins, whichemploy sequences from more than one species.

Methods well known in the art may be used to generate antibodies,polyclonal antisera, or monoclonal antibodies that are specific for aligand. Antibodies also may be produced as genetically engineeredimmunoglobulins (Ig) or Ig fragments designed to have desirableproperties. For example, by way of illustration and not limitation,antibodies may include a recombinant IgG that is a chimeric fusionprotein having at least one variable (V) region domain from a firstmammalian species and at least one constant region domain from a seconddistinct mammalian species. Most commonly, a chimeric antibody hasmurine variable region sequences and human constant region sequences.Such a murine/human chimeric immunoglobulin may be “humanized” bygrafting the complementarity determining regions (CDRs), which conferbinding specificity for an antigen, derived from a murine antibody intohuman-derived V region framework regions and human-derived constantregions. Fragments of these molecules may be generated by proteolyticdigestion, or optionally, by proteolytic digestion followed by mildreduction of disulfide bonds and alkylation, or by recombinant geneticengineering techniques.

Antibodies are defined to be “immunospecific” if they specifically bindthe ligand with an affinity constant, K_(a), of greater than or equal toabout 10⁴ M⁻¹, preferably of greater than or equal to about 10⁵ M⁻¹,more preferably of greater than or equal to about 10⁶ M⁻¹, and stillmore preferably of greater than or equal to about 10⁷ M⁻¹. Affinities ofbinding partners or antibodies can be readily determined usingconventional techniques, for example, those described by Scatchard etal., (Ann. N.Y. Acad. Sci. USA 51:660, 1949) or by surface plasmonresonance (BIAcore, Biosensor, Piscataway, N.J.) See, e.g., Wolff etal., Cancer Res., 53:2560-2565, 1993).

Antibodies for use in the present invention may be mono-specific,bi-specific, or even tri-specific. In this regard, the antibodies mayrecognize a single immunogen or may be engineered to recognize two orthree different immunogens.

Antibodies may generally be prepared by any of a variety of techniquesknown to those having ordinary skill in the art (See, e.g., Harlow etal, Antibodies: A Laboratory Manual, 1988, Cold Spring HarborLaboratory). In one such technique, an animal is immunized with theligand as antigen to generate polyclonal antisera. Suitable animalsinclude rabbits, sheep, goats, pigs, cattle, and may include smallermammalian species, such as, mice, rats, and hamsters.

An immunogen may be comprised of cells expressing the ligand, purifiedor partially purified ligand polypeptides or variants or fragmentsthereof, or ligand peptides. Ligand peptides may be generated byproteolytic cleavage or may be chemically synthesized. Peptides forimmunization may be selected by analyzing the primary, secondary, ortertiary structure of the ligand according to methods know to thoseskilled in the art in order to determine amino acid sequences morelikely to generate an antigenic response in a host animal (See, e.g.,Novotny, Mol. Immunol. 28:201-207, 1991; Berzoksky, Science 229:932-40,1985).

Preparation of the immunogen may include covalent coupling of the ligandpolypeptide or variant or fragment thereof, or peptide to anotherimmunogenic protein, such as, keyhole limpet hemocyanin or bovine serumalbumin. In addition, the peptide, polypeptide, or cells may be,emulsified in an adjuvant (See Harlow et al., Antibodies: A LaboratoryManual, 1988 Cold Spring Harbor Laboratory). In general, after the firstinjection, animals receive one or more booster immunizations accordingto a preferable schedule for the animal species. The immune response maybe monitored by periodically bleeding the animal, separating the sera,and analyzing the sera in an immunoassay, such as an Ouchterlony assay,to assess the specific antibody titer. Once an antibody titer isestablished, the animals may be bled periodically to accumulate thepolyclonal antisera. Polyclonal antibodies that bind specifically to theligand polypeptide or peptide may then be purified from such antisera,for example, by affinity chromatography using protein A or using theligand polypeptide or peptide coupled to a suitable solid support.

Monoclonal antibodies that specifically bind ligand polypeptides orfragments or variants thereof may be prepared, for example, using thetechnique of Kohler and Milstein (Nature, 256:495-497, 1975; Eur. J.Immunol. 6:511-519, 1976) and improvements thereto. Hybridomas, whichare immortal eukaryotic cell lines, may be generated that produceantibodies having the desired specificity to a the ligand polypeptide orvariant or fragment thereof. An animal—for example, a rat, hamster, orpreferably mouse—is immunized with the ligand immunogen prepared asdescribed above. Lymphoid cells, most commonly, spleen cells, obtainedfrom an immunized animal may be immortalized by fusion with adrug-sensitized myeloma cell fusion partner, preferably one that issyngeneic with the immunized animal. The spleen cells and myeloma cellsmay be, combined for a few minutes with a membrane fusion-promotingagent, such as polyethylene glycol or a nonionic detergent, and thenplated at low density on a selective medium that supports the growth ofhybridoma cells, but not myeloma cells. A preferred selection media isHAT (hypoxanthine, aminopterin, thymidine). After a sufficient time,usually about 1 to 2 weeks, colonies of cells are observed. Singlecolonies are isolated, and antibodies produced by the cells may betested for binding activity to the ligand polypeptide or variant orfragment thereof. Hybridomas producing antibody with high affinity andspecificity for the ligand antigen are preferred. Hybridomas thatproduce monoclonal antibodies that specifically bind to a ligandpolypeptide or variant or fragment thereof are contemplated by thepresent invention.

Monoclonal antibodies may be isolated from the supernatants of hybridomacultures. An alternative method for production of a murine monoclonalantibody is to inject the hybridoma cells into the peritoneal cavity ofa syngeneic mouse. The mouse produces ascites fluid containing themonoclonal antibody. Contaminants may be removed from the antibody byconventional techniques, such as chromatography, gel filtration,precipitation, or extraction.

Human monoclonal antibodies may be generated by any number oftechniques. Methods include but are not limited to, Epstein Barr Virus(EBV) transformation of human peripheral blood cells (see, U.S. Pat. No.4,464,456), in vitro immunization of human B cells (see, e.g., Boerneret al., J. Immunol. 147:86-95, 1991), fusion of spleen cells fromimmunized transgenic mice carrying human immunoglobulin genes and fusionof spleen cells from immunized transgenic mice carrying immunoglobulingenes inserted by yeast artificial chromosome (YAC) (see, e.g., U.S.Pat. No. 5,877,397; Bruggemann et al., Curr. Opin. Biotechnol. 8:455-58,1997; Jakobovits et al., Ann. N.Y. Acad. Sci. 764:525-35, 1995), orisolation from human immunoglobulin V region phage libraries.

Chimeric antibodies and humanized antibodies for use in the presentinvention may be generated. A chimeric antibody has at least oneconstant region domain derived from a first mammalian species and atleast one variable region domain derived from a second distinctmammalian species (See, e.g., Morrison et al., Proc. Natl. Acad. Sci.USA, 81:6851-55, 1984). Most commonly, a chimeric antibody may beconstructed by cloning the polynucleotide sequences that encode at leastone variable region domain derived from a non-human monoclonal antibody,such as the variable region derived from a murine, rat, or hamstermonoclonal antibody, into a vector containing sequences that encode atleast one human constant region. (See, e.g., Shin et al., MethodsEnzymol. 178:459-76, 1989; Walls et al., Nucleic Acids Res. 21:2921-29,1993). The human constant region chosen may depend upon the effectorfunctions desired for the particular antibody. Another method known inthe art for generating chimeric antibodies is homologous recombination(U.S. Pat. No. 5,482,856). Preferably, the vectors will be transfectedinto eukaryotic cells for stable expression of the chimeric antibody.

A non-human/human chimeric antibody may be further geneticallyengineered to create a “humanized” antibody. Such an antibody has aplurality of CDRs derived from an immunoglobulin of a non-humanmammalian species, at least one human variable framework region, and atleast one human immunoglobulin constant region. Humanization may yieldan antibody that has decreased binding affinity when compared with thenon-human monoclonal antibody or the chimeric antibody. Those havingskill in the art, therefore, use one or more strategies to designhumanized antibodies.

Within certain embodiments, the use of antigen-binding fragments ofantibodies may be preferred. Such fragments include Fab fragments orF(ab′)₂ fragments, which may be prepared by proteolytic digestion withpapain or pepsin, respectively. The antigen binding fragments may beseparated from the Fc fragments by affinity chromatography, for example,using immobilized protein A or immobilized ligand polypeptide or avariant or a fragment thereof. An alternative method to generate Fabfragments includes mild reduction of F(ab′)₂ fragments followed byalkylation (See, e.g., Weir, Handbook of Experimental Immunology, 1986,Blackwell Scientific, Boston).

Non-human, human, or humanized heavy chain and light chain variableregions of any of the above described Ig molecules may be constructed assingle chain Fv (sFv) fragments (single chain antibodies). See, e.g.,Bird et al., Science 242:423-426, 1988; Huston et al., Proc. Natl. Acad.Sci. USA 85:5879-5883, 1988. Multi-functional fusion proteins may begenerated by linking polynucleotide sequences encoding an sFv in-framewith polynucleotide sequences encoding various effector proteins. Thesemethods are known in the art, and are disclosed, for example, inEP-B1-0318554, U.S. Pat. No. 5,132,405, U.S. Pat. No. 5,091,513, andU.S. Pat. No. 5,476,786.

An additional method for selecting antibodies that specifically bind toa ligand polypeptide or variant or fragment thereof is by phage display(See, e.g., Winter et al., Annul. Rev. Immunol. 12:433-55, 1994; Burtonet al., Adv. Immunol. 57:191-280, 1994). Human or murine immunoglobulinvariable region gene combinatorial libraries may be created in phagevectors that can be screened to select Ig fragments (Fab, Fv, sFv, ormultimers thereof) that bind specifically to a ligand polypeptide orvariant or fragment thereof (See, e.g., U.S. Pat. No. 5,223,409; Huse etal., Science 246:1275-81, 1989; Kang et al., Proc. Natl. Acad. Sci. USA88:4363-66, 1991; Hoogenboom et al., J. Molec. Biol. 227:381-388, 1992;Schlebusch et al., Hybridoma 16:47-52, 1997 and references citedtherein).

In certain aspects of the present invention other agents can be used inthe generation of EMSP, including but not limited to fusion proteinscomprising natural ligands that bind to T cell surface molecules. In oneembodiment, fusion proteins can be generated such that Ig Fc portionsare fused to a natural ligand of interest. Such a fusion protein couldthen be loaded onto an EMSP as described herein that expresses an Fcγreceptor.

Cell Populations

As discussed above, the present invention has broad applicability to anycell type having a cell surface moiety that one is desirous of ligating.In this regard, many cell signaling events can be enhanced by themethods of the present invention. Such methodologies can be usedtherapeutically in an ex vivo setting to activate and stimulate cellsfor infusion into a patient or could be used in vivo, to induce cellsignaling events on a target cell population. However, as also notedabove, the prototypic example provided herein is directed to T cells,but is in no way limited thereto.

With respect to T cells, the T cell populations resulting from thevarious expansion methodologies described herein may have a variety ofspecific phenotypic properties, depending on the conditions employed.Such phenotypic properties include enhanced expression of CD25, CD154,IFN-γ and GM-CSF, as well as altered expression of CD137, CD134, CD62L,and CD49d. The ability to differentially control the expression of thesemoieties may be very important. For example, higher levels of surfaceexpression of CD154 on “tailored T cells,” through contact with CD40molecules expressed on antigen-presenting cells (such as dendriticcells, monocytes, and even leukemic B cells or lymphomas), will enhanceantigen presentation and immune function. Such strategies are currentlybeing employed by various companies to ligate CD40 via antibodies orrecombinant CD40L. The approach described herein permits this samesignal to be delivered in a more physiological manner, e.g., by the Tcell. The ability to increase IFN-γ secretion by tailoring the T cellactivation process could help promote the generation of TH1-type immuneresponses, important for anti-tumor and anti-viral responses. LikeCD154, increased expression of GM-CSF can serve to enhance APC function,particularly through its effect on promoting the maturation of APCprogenitors into more functionally competent APC, such as dendriticcells. Altering the expression of CD137 and CD134 can effect a T cell'sability to resist or be susceptible to apoptotic signals. Controllingthe expression of adhesion/homing receptors, such as CD62L and/or CD49dmay determine the ability of infused T cells to home to lymphoid organs,sites of infection, or tumor sites.

An additional aspect of the present invention provides a T cellpopulation or composition that has been depleted of CD8⁺ or CD4⁺ cellsprior to expansion. In one embodiment, CD8⁺ cells are depleted byantibodies directed to the CD8⁺ marker. One of ordinary skill in the artwould readily be able to identify a variety of particular methodologiesfor depleting a sample of CD8⁺ or CD4⁺ cells or conversely enriching theCD4⁺ or CD8⁺ cell content. With respect to enriching for CD4⁺ cells, oneaspect of the present invention is focused on the identification of anextremely robust CD154 expression profile upon stimulation of T cellpopulations wherein T_(C) (CD8⁺) cells have been depleted. As indicatedabove, CD 154 is an important immunomodulating molecule whose expressionis extremely beneficial in amplifying the immune response. Accordinglyan increase in CD154 expression is likely to lead to more efficacious Tcell compositions.

An additional aspect of the present invention provides a T cellpopulation or composition that has been depleted or enriched forpopulations of cells expressing a variety of markers, such as CD62L,CD45RA or CD45RO, cytokines (e.g., IL-2, IFN-γ, IL-4, IL-10), cytokinereceptors (e.g., CD25), perforin, adhesion molecules (e.g., VLA-1,VLA-2, VLA-4, LPAM-1, LFA-1), and/or homing molecules (e.g.,L-Selectin), prior to expansion. In one embodiment, cells expressing anyof these markers are depleted or positively selected by antibodies orother ligands/binding agents directed to the marker. One of ordinaryskill in the art would readily be able to identify a variety ofparticular methodologies for depleting or positively selecting for asample of cells expressing a desired marker.

The phenotypic properties of T cell populations of the present inventioncan be monitored by a variety of methods including standard flowcytometry methods and ELISA methods known by those skilled in the art.

T cell populations of the present invention may also be antigen-specificT cells, for example, tumor-antigen-specific T cells or hTERT-specific Tcells as described herein. In certain embodiments, antigen-specific Tcells can be isolated from a patient of interest, such as a patientafflicted with a cancer or an infectious disease as described herein. Incertain embodiments, antigen-specific T cells can be induced byvaccination of a patient with a particular antigen, either alone or inconjunction with an adjuvant or pulsed on dendritic cells.

In certain embodiments, it may be desirable to sort or otherwisepositively select the antigen specific cells prior to or following oneor two rounds of expansion with EMSP. It may be desirable to sort orpositively select cells directly from an individual, for example apatient who has been vaccinated with a particular antigen of interest.In certain embodiments, the activated T cells may have been exposed toan APC pulsed with or expressing an antigen of interest, eithernaturally in vivo, or through vaccination. Further, in certainembodiments, the specific T cells to be positively selected or otherwisesorted may have been exposed to an APC pulsed with or expressing anantigen of interest in vitro. Sorting or positively selectingantigen-specific cells can be carried out using peptide-MHC tetramers(Altman, et al., Science. 1996 Oct. 4; 274(5284):94-6.). In anotherembodiment antigen-specific T cells are isolated or otherwise positivelyselected by contacting said T cells with antibodies specific for T cellactivation markers. Antibodies that can be used with the methods of thepresent invention include, but are not limited to, anti-CD25, anti-CD54,anti-CD69, anti-CD38, anti-CD45RO, anti-CD49d, anti-CD40L, anti-CD137,and anti-CD134 antibodies. Sorting of antigen-specific T cells, orgenerally any cells of the present invention, can be carried out usingany of a variety of commercially available cell sorters, including, butnot limited to, MoFlo sorter (DakoCytomation, Fort Collins, Colo.),FACSAria™, FACSArray™, FACSVantage™, BD™ LSR II, and FACSCalibur™ (BDBiosciences, San Jose, Calif.).

Methods of Use

In addition to the methods described above, the EMSP described hereinand the cells stimulated and/or activated by the methods hereindescribed may be utilized in a variety of contexts. With respect to theprototypic example of T cells, the methodologies described herein can beused to selectively activate and expand a population expressing any oneor more of CD28, CD4, CD8, Bcl-xL, CD45RA, or CD45RO for use in thetreatment of infectious diseases and cancer, and generally inimmunotherapy. As a result, a phenotypically unique population of Tcells, which is polyclonal with respect to antigen reactivity, butessentially homogeneous with respect to either CD4⁺ or CD8⁺ can beproduced. In addition, the method allows for the expansion of apopulation of T cells in numbers sufficient to reconstitute anindividual's total CD4⁺ or CD8⁺ T cell population (the population oflymphocytes in an individual is approximately 3-5×10¹¹). The resulting Tcell population can also be genetically transduced and used forimmunotherapy or can be used in methods of in vitro analyses ofinfectious agents. For example, a population of tumor-infiltratinglymphocytes can be obtained from an individual afflicted with cancer andthe T cells stimulated to proliferate to sufficient numbers. Theresulting T cell population can be genetically transduced to expresstumor necrosis factor (TNF) or other proteins (for example, any numberof cytokines, inhibitors of apoptosis (e.g., Bcl-2), genes that protectcells from HIV infection such as RevM10 or intrakines, and the like,targeting molecules, adhesion and/or homing molecules and any variety ofantibodies or fragments thereof (e.g., Scfv)) and given to theindividual.

In certain embodiments, the EMSP of the present invention can becontacted with paramagnetic particles such that said paramagneticparticles are engulfed by the EMSP. EMSP comprising paramagneticparticles can then be subjected to magnetic force and concentrated orlocalized to a particular site of interest, such as a tumor, site ofviral infection or site of autoimmune disease, and/or otherwiseselected, either in vitro or in vivo.

Likewise, the EMSP of the present invention can be used in vivo or exvivo to stimulate tumor-specific T cells, autoantigen-specific T cells,and or viral-specific T cells. Within this context, in certainembodiments, the EMSP can be generated such that tolerance to suchtumor, auto, or viral antigens is broken, either in an in vivo or invitro setting. In an in vivo setting, the EMSP can be administeredlocally to a tumor site, a site of viral infection or site of autoimmunedisease, or alternatively can be administered systemically. T cells thathave been stimulated using the EMSP as described herein can then beinfused into a patient.

One particular use for the CD4⁺ T cells populations of the invention isthe treatment of HIV infection in an individual. Prolonged infectionwith HIV eventually results in a marked decline in the number of CD4⁺ Tlymphocytes. This decline, in turn, causes a profound state ofimmunodeficiency, rendering the patient susceptible to an array of lifethreatening opportunistic infections. Replenishing the number of CD4⁺ Tcells to normal levels may be expected to restore immune function to asignificant degree. Thus, the method described herein provides a meansfor selectively expanding CD4⁺ T cells to sufficient numbers toreconstitute this population in an HIV infected patient. It may also benecessary to avoid infecting the T cells during long-term stimulation orit may desirable to render the T cells permanently resistant to HIVinfection. There are a number of techniques by which T cells may berendered either resistant to HIV infection or incapable of producingvirus prior to restoring the T cells to the infected individual. Forexample, one or more anti-retroviral agents can be cultured with CD4⁺ Tcells prior to expansion to inhibit HIV replication or viral production(e.g., drugs that target reverse transcriptase and/or other componentsof the viral machinery, see e.g., Chow et al., Nature 361:650-653,1993).

Several methods can be used to genetically transduce T cells to producemolecules which inhibit HIV infection or replication. For example, invarious embodiments, T cells can be genetically transduced to producetransdominant inhibitors, “molecular decoys”, antisense molecules,intrakines, or toxins. Such methodologies are described in furtherdetail in U.S. patent application Ser. Nos. 08/253,751, 08/253,964, andPCT Publication No. WO 95/33823, which are incorporated herein byreference in their entirety.

The methods for stimulating and expanding a population of antigenspecific T cells are useful in therapeutic situations where it isdesirable to up-regulate an immune response (e.g., induce a response orenhance an existing response) upon administration of the T cells to asubject. For example, the method can be used either in vivo or in vitroto enhance a T cell response against tumor-associated antigens. Tumorcells from a subject typically express tumor-associated antigens but maybe unable to stimulate a co-stimulatory signal in T cells (e.g., becausethey lack expression of co-stimulatory molecules). Thus, as describedherein tumor cells, or antigen derived therefrom, can be contacted withT cells from the subject in vitro and the resultingtumor-antigen-specific T cells expanded according to the method of theinvention and the specific T cells returned to the subject.Additionally, in certain embodiments, it may be desirable to contact Tcells with tumor antigen in vivo, e.g., via vaccination. Followingvaccination, the specific T cells may be isolated and contacted in vitroand expanded with the EMSP according to the method of the invention. Incertain embodiments, the desired antigen-specific T cells can be sortedor isolated using peptide-MHC tetramers or antibodies specific for Tcell activation markers. The sorted antigen-specific cells can befurther expanded using the methods described herein and returned to thesubject. Further, one of ordinary skill in the art would readilyunderstand that treatment of a patient with ex vivo expanded T cells ofthe present invention may be combined with traditional cancer therapiessuch as chemotherapy. In this regard, for example, a patient may betreated with an agent such as Fludarabine or Campath (BerlexLaboratories, Montville, N.J., USA), followed by infusion with T cellpopulations of the present invention.

The present invention thus provides methods for preventing, inhibiting,or reducing the presence of a cancer or malignant cells in an animal,which comprise administering to an animal an anti-cancer effectiveamount of the subject EMSP with or without activated T cells. Further,as noted above, the EMSP and activated T cells of the present inventionmay be combined with traditional cancer therapies.

The cancers contemplated by the present invention, against which theimmune response is induced, or which is to be prevented, inhibited, orreduced in presence, may include but are not limited to melanoma,non-Hodgkin's lymphoma, Hodgkin's disease, leukemia, plasmocytoma,sarcoma, glioma, thymoma, breast cancer, prostate cancer, colo-rectalcancer, kidney cancer, renal cell carcinoma, pancreatic cancer,esophageal cancer, brain cancer, lung cancer, ovarian cancer, cervicalcancer, multiple myeloma, hepatocellular carcinoma, nasopharyngealcarcinoma, LGL, ALL, AML, CML, CLL, and other neoplasms known in theart.

Accordingly, in one embodiment malignancies such as non-HodgkinsLymphoma (NHL) and B-cell chronic lymphocytic leukemia (B-CLL) can betreated. While initial studies using expanded T cells have been testedin NHL, (see Liebowitz et al., Curr. Opin. Onc. 10:533-541, 1998), the Tcell populations of the present invention offer unique phenotypiccharacteristics that can dramatically enhance the success ofimmunotherapy by providing increased engraftment (likely supplied bystimulation of the CD28 signal) and reactivity. However, patients withB-CLL present special difficulties, including low relative T cellnumbers with high leukemic cell burden in the peripheral blood,accompanied by a general T cell immunosuppression. The T cellpopulations of the present invention can provide dramatically improvedefficacy in treating this disease and especially when combined with stemcell transplantation therapy. Accordingly, increasing T cell functionand anti-CLL T cell activity with EMSP would be beneficial.

For example, given that deficient expression of CD154, the ligand forCD40, on T cells of B-CLL patients has been cited as a majorimmunological defect of the disease, the T cell populations of thepresent invention, which may provide sustained high levels of CD154expression upon infusion, could aid in its treatment. Investigatorsreport that in CLL the capability of a patient's T cells' to expressCD154 is defective as well as the capability of the leukemic B-cells toexpress CD80 and CD86. The failure of leukemic B-cells in CLL toadequately express the ligands for CD28, could result in failure tofully activate tumor-responsive T cells and, therefore, may representthe mechanism underlying the T cells' apparent state of tolerance.Studies in which CD40 is engaged on CLL B cells, either via solubleanti-CD40 antibodies or via CD154-transduced leukemic B-cells, appearsto correct the defect in CD80 and CD86 expression and up-regulates MHCsurface expression. Kato et al, J. Clin. Invest. 101:1133-1141, 1998;Ranheim and Kipps, J. Exp. Med. 177:925-935, 1993. Cells treated in thisway were able to stimulate specific T cell anti-tumor responses.

With the enhanced expression of CD 154 on the surface of the T cellpopulation of the present invention such T cells would be expected tointeract with autologous B-CLL cells, and would thus increase thattumor's immunogenicity by driving up expression of MHC, CD80, and CD86.This, in turn, should lead to a strong anti-tumor response. Further, oneof ordinary skill in the art would readily understand that treatment ofa patient with ex vivo expanded T cells of the present invention may becombined with traditional cancer therapies such as chemotherapy. In thisregard, for example, a patient may be treated with an agent such asFludarabine or Campath (Berlex Laboratories, Montville, N.J., USA),followed by infusion with T cell populations of the present invention orboth.

Compositions as described herein can be used to induce or enhanceresponsiveness to pathogenic organisms, such as viruses, (e.g., singlestranded RNA viruses, single stranded DNA viruses, double-stranded DNAviruses, HIV, hepatitis A, B, and C virus, HSV, CMV, EBV, HPV),parasites (e.g., protozoan and metazoan pathogens such as Plasmodiaspecies, Leishmania species, Schistosoma species, Trypanosoma species),bacteria (e.g., Mycobacteria, Salmonella, Streptococci, E. coli,Staphylococci), fungi (e.g., Candida species, Aspergillus species) andPneumocystis carinii.

The invention further provides methods to selectively expand a specificsubpopulation of T cells from a mixed population of T cells. In oneembodiment, the invention provides specifically enriched populations ofT cells that have much higher ratio of CD4⁺ and CD8⁺ double positive Tcells. In an additional embodiment, the invention provides methods toselectively expand CD8⁺ T cells expressing increased levels of Bcl-xL.

Another embodiment of the invention, provides a method for selectivelyexpanding a population of T_(H1) cells from a population of CD4⁺ Tcells. In this method, CD4⁺ T cells are co-stimulated with an anti-CD28antibody, such as the monoclonal antibody 9.3, inducing secretion ofT_(H1)-specific cytokines, including IFN-γ, resulting in enrichment ofT_(H1) cells over T_(H2) cells. In a further embodiment, methods areprovided for selectively expanding Tc1 over Tc2 cells, or vice versa.Tc1 and Tc2 cells can be distinguished based on cytokine secretionpatterns using any number of assays known to the skilled artisan.

T cells have been demonstrated to be activated within a few hours (Iezziet al., Immunity 8:89-95, 1998). Accordingly, in combination with themethodologies herein described, this provides the ability to expand atailor made subset of a T cell population in a short period of time. Inone embodiment, this technique can be utilized at the bedside of asubject, in an outpatient modality, or at a subject's home, similar tothe use of kidney dialysis. For example, a method or device wherein Tcells are incubated in contact with activation signals (e.g., anti-CD3and anti-CD28 antibodies, and the like) and returned to the patientimmediately in a continuous flow or after a few hour expansion period.In one aspect, such techniques of expansion could use isolated chamberswith filter components, such that EMSP are mixed with a continuous flowof blood/concentrated cells. In another embodiment, EMSP within anapparatus may be provided to stimulate T cell activation and expansion.For example, a continuous fluid path from the patient through ablood/cell collection device and/or a disposable device containing EMSPand/or other components to stimulate T cells prior to cells returning tothe subject can be utilized. Such a system could involve a leukapheresisinstrument with a disposable set sterile docked to the existingmanufacturers disposable set, or be an adaptation to the manufacturer'sdisposable set. Further, the EMSP may be a part of a removal insertwhich is inserted into one of the device chambers or physically presentwithin one of the disposable components. In another embodiment of thecontinuous flow aspect discussed above, the system may comprisecontacting the cells with the activating components at room temperatureor at physiologic temperature using a chamber within a blood collectiondevice or an incubation chamber set up in series with the flow path tothe patient.

In another example, blood is drawn into a stand-alone disposable devicedirectly from the patient that contains EMSP. In one embodiment, thedisposable device may comprise a container (e.g., a plastic bag, orflask) with appropriate tubing connections suitable forcombining/docking with syringes and sterile docking devices. This devicewill contain a EMSP for immobilization of T cell activation components(e.g., anti-CD3 and anti-CD28 antibodies); Additionally when using thestand-alone device, the subject can remain connected to the device, orthe device can be separable from the patient. Further, the device may beutilized at room temperature or incubated at physiologic temperatureusing a portable incubator.

As devices and methods for collecting and processing blood and bloodproducts are well known, one of skill in the art would readily recognizethat given the teachings provided herein, that a variety of devices thatfulfill the needs set forth above may be readily designed or existingdevices modified. Accordingly, as such devices and methods are notlimited by the specific embodiments set forth herein, but would includeany device or methodology capable of maintaining sterility and whichmaintains blood in a fluid form in which complement activation isreduced and wherein components necessary for T cell activation (e.g.,anti-CD3 and anti-CD28 antibodies or ligands thereto) may be separatedfrom the blood or blood product prior to administration to the subject.Further, as those of ordinary skill in the art can readily appreciate avariety of blood products can be utilized in conjunction with thedevices and methods described herein. For example the methods anddevices could be used to provide rapid activation of T cells fromcryopreserved whole blood, peripheral blood mononuclear cells, othercyropreserved blood-derived cells, or cryopreserved T cell lines uponthaw and prior to subject administration: In another example, themethods and devices can be used to boost the activity of a previously exvivo expanded T cell product or T cell line prior to administration tothe subject, thus providing a highly activated T cell product. Lastly,as will be readily appreciated the methods and devices above may beutilized for autologous or allogeneic cell therapy simultaneously withthe subject and donor.

The methods of the present invention may also be utilized with vaccinesto enhance reactivity of the antigen and enhance in vivo effect.Further, given that T cells expanded by the present invention have arelatively long half-life in the body, these cells could act as perfectvehicles for gene therapy, by carrying a desired nucleic acid sequenceof interest and potentially homing to sites of cancer, disease, orinfection. Accordingly, the cells expanded by the present invention maybe delivered to a patient in combination with a vaccine, one or morecytokines, one or more therapeutic antibodies, or in combination withthe EMSP as described herein. Virtually any therapy that would benefitby a more robust T cell population is within the context of the methodsof use described herein.

In a further embodiment of the present invention, EMSP may be used toexpand antigen-specific T cells. In this regard, any number of sourcesof antigen-specific T cells can be used. In certain embodiments,tumor-specific T cells can be isolated from a cancer patient. In certainembodiments, the antigen-specific T cells are induced by vaccination ofa patient with a particular antigen, either alone or in conjunction withan adjuvant or pulsed on dendritic cells. In one embodiment,tumor-specific T cells can be expanded in vivo using the EMSP of thepresent invention, either alone, or following vaccination with anantigen of interest. In certain embodiments, the EMSP can be pulsed withor modified to express an antigen of interest.

Antigen-specific cells for use in expansion using the EMSP of thepresent invention may also be generated in vitro using any number ofmethods known in the art, for example, as described in U.S. PatentApplication No. 60/469,122 entitled GENERATION AND ISOLATION OFANTIGEN-SPECIFIC T CELLS, filed May 8, 2003, or in U.S. Pat. Nos.6,040,177 and 5,872,642. Antigen-specific cells for use in expansionusing the EMSP of the present invention may also be generated using anynumber of methods known in the art, for example, as described in CurrentProtocols in Immunology, or Current Protocols in Cell Biology, bothpublished by John Wiley & Sons, Inc., Boston, Mass. In a relatedembodiment, it may be desirable to sort the antigen specific cells priorto, or even following one or two rounds of expansion with EMSP. Sortingof antigen-specific cells can be carried out using peptide-MHC tetramersas described herein or antibodies specific for any number of markers ofmemory T cells (including but not limited to, anti-CD25, anti-CD54,anti-CD69, anti-CD38, anti-CD45RO, anti-CD49d, anti-CD40L, anti-CD137,and anti-CD134 antibodies). Sorting of antigen-specific T cells, orgenerally any cells of the present invention, can be carried out usingany of a variety of commercially available cell sorters, including, butnot limited to, MoFlo sorter (DakoCytomation, Fort Collins, Colo.),FACSAria™, FACSArray™, FACSVantage™, BD™ LSR II, and FACSCalibur™ (BDBiosciences, San Jose, Calif.).

As noted elsewhere herein, the cell compositions of the presentinvention comprising EMSP and/or activated T cells can be used inconjunction with other cancer therapies, including but not limited tochemotherapy, radiation, or treatment with agents such as cyclosporin,azathioprine, methotrexate, mycophenolate, and FK506, antibodies, orother immunoablative agents such as CAMPATH, anti-CD3 antibodies,cyclophosphamide, fludaribine, cyclosporin, FK506, rapamycin,mycophenolic acid, steroids, FR901228, and irradiation. These drugsinhibit either the calcium dependent phosphatase calcineurin(cyclosporine and FK506) or inhibit the p70S6 kinase that is importantfor growth factor induced signaling (rapamycin). (Liu et al., Cell66:807-815, 1991; Henderson et al., Immun. 73:316-321, 1991; Bierer etal., Curr. Opin. Immun. 5:763-773, 1993; Isoniemi (supra)). Further, thecompositions of the present invention comprising EMSP and/or activated Tcells can be used in conjunction with other treatment modalities, e.g.,any treatments desirable in the setting of any of the infectiousdiseases described herein, such as antiviral, antibacterial, or antifungal agents.

Pharmaceutical Compositions

The EMSP and/or the target cell populations, such as T cell populationsof the present invention may be administered either alone, or as apharmaceutical composition in combination with diluents and/or withother components such as IL-2 or other cytokines or cell populations.Briefly, pharmaceutical compositions of the present invention maycomprise an EMSP or a target cell population as described herein, incombination with one or more pharmaceutically or physiologicallyacceptable carriers, diluents or excipients. Such compositions maycomprise buffers such as neutral buffered saline, phosphate bufferedsaline and the like; carbohydrates such as glucose, mannose, sucrose ordextrans, mannitol; proteins; polypeptides or amino acids such asglycine; antioxidants; chelating agents such as EDTA or glutathione;adjuvants (e.g., aluminum hydroxide); and preservatives. Compositions ofthe present invention are preferably formulated for intravenousadministration.

Pharmaceutical compositions of the present invention may be administeredin a manner appropriate to the disease to be treated (or prevented). Thequantity and frequency of administration will be determined by suchfactors as the condition of the patient, and the type and severity ofthe patient's disease, although appropriate dosages may be determined byclinical trials.

Pharmaceutical compositions of the present invention may be administeredin a manner appropriate to the disease to be treated (or prevented). Thequantity and frequency of administration will be determined by suchfactors as the condition of the patient, and the type and severity ofthe patient's disease, although appropriate dosages may be determined byclinical trials.

The present invention also provides methods for preventing, inhibiting,or reducing the presence of a cancer or malignant cells in an animal,which comprise administering to an animal an anti-cancer effectiveamount of the subject EMSP with or without activated T cells.

The cancers contemplated by the present invention, against which theimmune response is induced, or which is to be prevented, inhibited, orreduced in presence, may include but are not limited to melanoma,non-Hodgkin's lymphoma, Hodgkin's disease, leukemia, plasmocytoma,sarcoma, glioma, thymoma, breast cancer, prostate cancer, colo-rectalcancer, kidney cancer, renal cell carcinoma, pancreatic cancer,esophageal cancer, brain cancer, lung cancer, ovarian cancer, cervicalcancer, multiple myeloma, hepatocellular carcinoma, nasopharyngealcarcinoma, ALL, AML, CML, CLL, and other neoplasms known in the art.

Alternatively, compositions as described herein can be used to induce orenhance responsiveness to pathogenic organisms, such as viruses, (e.g.single stranded RNA viruses, single stranded DNA viruses,double-stranded DNA viruses, HIV, hepatitis A, B, and C virus, HSV, CMV,EBV, HPV), parasites (e.g., protozoan and metazoan pathogens such asPlasmodia species, Leishmania species, Schistosoma species, Trypanosomaspecies), bacteria (e.g., Mycobacteria, Salmonella, Streptococci, E.coli, Staphylococci), fungi (e.g., Candida species, Aspergillus species)and Pneumocystis carinii.

The immune response induced in the animal by administering the subjectcompositions of the present invention may include cellular immuneresponses mediated by CD8⁺ T cells, capable of killing tumor andinfected cells, and CD4⁺ T cell responses. Humoral immune responses,mediated primarily by B cells that produce antibodies followingactivation by CD4⁺ T cells, may also be induced. A variety of techniquesmay be used for analyzing the type of immune responses induced by thecompositions of the present invention, which are well described in theart; e.g., Coligàn et al., Current Protocols in Immunology, John Wiley &Sons Inc., 1994.

When “an immunologically effective amount,” “an anti-tumor effectiveamount,” “a tumor-inhibiting effective amount,” or “therapeutic amount”is indicated, the precise amount of the compositions of the presentinvention to be administered can be determined by a physician withconsideration of individual differences in age, weight, tumor size,extent of infection or metastasis, and condition of the patient. It cangenerally be stated that a pharmaceutical composition comprising thesubject EMSP and/or activated T cells, may be administered at a dosageto be determined during appropriate clinical trials. EMSP compositionsmay also be administered multiple times at these dosages. The cells canbe administered by using infusion techniques that are commonly known inimmunotherapy (see, e.g., Rosenberg et al., New Eng. J. of Med. 319:1676, 1988). The optimal dosage and treatment regime for a particularpatient can readily be determined by one skilled in the art of medicineby monitoring the patient for signs of disease and adjusting thetreatment accordingly.

Activated T cells will be administered in dosages and routes and attimes to be determined in appropriate clinical trials. T cellcompositions may be administered multiple times at dosages within theseranges. The EMSP-based method of therapy may be combined with othermethods, such as direct administration of the activated T cells of theinvention. The activated T cells and EMSP may be autologous orheterologous to the patient undergoing therapy. If desired, thetreatment may also include administration of mitogens (e.g., PHA) orlymphokines, cytokines, and/or chemokines (e.g., GM-CSF, IL-4, IL-13,Flt3-L, RANTES, MIP1-α, etc.) as described herein to enhance inductionof the immune response.

The administration of the subject pharmaceutical compositions may becarried out in any convenient manner, including by aerosol inhalation,injection, ingestion, transfusion, implantation or transplantation. Thecompositions of the present invention may be administered to a patientsubcutaneously, intradermally, intramuscularly, by intravenous (i.v.)injection, or intraperitoneally. Preferably, the EMSP compositions ofthe present invention are administered to a patient by intradermal orsubcutaneous injection. The T cell compositions of the present inventionare preferably administered by i.v. injection. The compositions of EMSPor activated T cells may be injected directly into a tumor or lymphnode.

In yet another embodiment, the pharmaceutical composition can bedelivered in a controlled release system. In one embodiment, a pump maybe used (see Langer, Science 249: 1527-33, 1990; Sefton, CRC Crit. Ref.Biomed. Eng. 14:201, 1987; Buchwald et al., Surgery 88:507, 1980; Saudeket al., N. Engl. J. Med. 321:574, 1989). In another embodiment,polymeric materials can be used (see Langer and Wise (eds.), MedicalApplications of Controlled Release, CRC Pres., Boca Raton, Fla., 1974;Smolen and Ball (eds.), Controlled Drug Bioavailability, “Drug ProductDesign and Performance,” Wiley, New York, 1984; Ranger and Peppas, J.Macromol. Sci. Rev. Macromol. Chem. 23:61, 1983; see also Levy et al.,Science 228:190 1985; During et al., Ann. Neurol. 25:351, 1989; Howardet al., J. Neurosurg. 71: 105, 1989). In yet another embodiment, acontrolled release system can be placed in proximity of the therapeutictarget, thus requiring only a fraction of the systemic dose (see, e.g.,Langer and Wise (eds.), Medical Applications of Controlled Release, CRCPres., Boca Raton, Fla., 1984, vol. 2, pp. 115-138).

The EMSP and T cell compositions of the present invention may also beadministered using any number of matrices. Matrices have been utilizedfor a number of years within the context of tissue engineering (see,e.g., Lanza, Langer, and Chick (eds.), Principles of Tissue Engineering,1997). The present invention utilizes such matrices within the novelcontext of acting as an artificial lymphoid organ to support, maintain,or modulate the immune system, typically through modulation of T cells.Accordingly, the present invention can utilize those matrix compositionsand formulations which have demonstrated utility in tissue engineering.Accordingly, the type of matrix that may be used in the compositions,devices and methods of the invention is virtually limitless and mayinclude both biological and synthetic matrices. In one particularexample, the compositions and devices set forth by U.S. Pat. Nos.5,980,889; 5,913,998; 5,902,745; 5,843,069; 5,787,900; or 5,626,561 areutilized, as such these patents are incorporated by reference in theirentirety. Matrices comprise features commonly associated with beingbiocompatible when administered to a mammalian host. Matrices may beformed from natural and/or synthetic materials. The matrices may benon-biodegradable in instances where it is desirable to leave permanentstructures or removable structures in the body of an animal, such as animplant; or biodegradable. The matrices may take the form of sponges,implants, tubes, telfa pads, fibers, hollow fibers, lyophilizedcomponents, gels, powders, porous compositions, or nanoparticles. Inaddition, matrices can be designed to allow for sustained release ofseeded cells or produced cytokine or other active agent. In certainembodiments, the matrix of the present invention is flexible andelastic, and may be described as a semisolid scaffold that is permeableto substances such as inorganic salts, aqueous fluids and dissolvedgaseous agents including oxygen.

A matrix is used herein as an example of a biocompatible substance.However, the current invention is not limited to matrices and thus,wherever the term matrix or matrices appears these terms should be readto include devices and other substances which allow for cellularretention or cellular traversal, are biocompatible, and are capable ofallowing traversal of macromolecules either directly through thesubstance such that the substance itself is a semi-permeable membrane orused in conjunction with a particular semi-permeable substance.

In one aspect of the present invention, the EMSP described herein can beused in vivo as an adjuvant as described in U.S. Pat. No. 6,464,973. Ina further embodiment, the EMSP can be used as a vaccine to induce animmune response in vivo against an antigen of interest such as thosedescribed herein (e.g., tumor antigens, viral antigens, autoantigens,etc). In one embodiment the EMSP can be used to generate an immuneresponse in vivo, either administered alone or in combination withactivated T cells as described herein or in combination with other knowntherapies.

In one embodiment of the present invention, EMSP may be used to generatepolyclonal and/or antigen-specific T cells in vitro or in vivo. T cellsmay be stimulated with EMSP loaded or engineered to express antigen inthe context of MHC as previously described. Such stimulation isperformed under conditions and for a time sufficient to permit thegeneration of T cells that are specific for the antigen of interest. Forexample, T cells (5×10⁶ cells/ml) and antigen-loaded or expressing EMSP(2.5×10⁵ cells/ml) may be cultured in conventional media as describedherein, supplemented with 5-10% serum, 1 mM sodium pyruvate, with orwithout 100 IU/ml penicillin, with or without 100 μg/ml streptomycin,and 5×10⁻⁵ M β-mercaptoethanol in 96 well U-bottom plates at a ratio of20:1. After 5 days, cells may be tested for antigen-specificity in astandard 4 hours chromium release assay. Antigen-specific T cells may befurther expanded using techniques known in the art (as described in U.S.Pat. No. 5,827,642) or as described herein. Stimulation of T cells withEMSP as described in the Examples may be carried out following thestimulation with antigen-loaded EMSP to further increase expansion ofthe desired antigen-specific T cells.

All references referred to within the text are hereby incorporated byreference in their entirety. Moreover, all numerical ranges utilizedherein explicitly include all integer values within the range andselection of specific numerical values within the range is contemplateddepending on the particular use. Further, the following examples areoffered by way of illustration, and not by way of limitation.

EXAMPLES Protocols

The constructions described below are carried out according to thegeneral techniques of genetic engineering and molecular cloning detailedin, e.g., Maniatis et al., (Laboratory Manual, Cold Spring Harbor,Laboratory Press, Cold Spring Harbor, N.Y. (1989)). The steps of PCRamplification follow known protocols, as described in, e.g., PCRProtocols—A Guide to Methods and Applications (ed., Innis, Gelfand,Sninsky and White, Academic Press Inc. (1990)). Notably, theoligonucleotides used to modify the Ad genome may use differentrestriction enzyme sites than those identified below, and may use aslightly different insertion site in the genome, without affecting theoutcome of the invention. Such variations, so long as not substantial,are within the understanding of one of ordinary skill in the art.

Moreover, cells are transfected according to standard techniques, wellknown to a person skilled in the art. Protocols enabling a nucleic acidto be introduced into a cell may employ known methods, e.g., calciumphosphate transfection (Maniatis et al., 1989), DEAE-dextran techniques,electroporation, methods based on osmotic shocks, micro-injection of theselected cell, or methods based on the use of liposomes.

Cloning and construction of cell-based artificial APC (aAPC). Human CD32was cloned from neutrophils into the pcDNA 3.1 neo vector (Invitrogen,Carlsbad, Calif.), and transfected into K562 cells (American TypeCulture Collection, Manassas, Va.) by electroporation; K32 cells werecloned by FACS sorting. Similarly, (h)4-1BB ligand was cloned from Bcells into the pcDNA3.1 hygro vector (Invitrogen), and transfected intoK32 cells before FACS sorting.

CD8⁺ T lymphocyte preparation and K562 cell culture. Fresh peripheralblood lymphocytes were obtained by leukopheresis and elutriation. CD4⁺ Tcells were purified by negative selection using the OKT4 Ab (ATCC) asdescribed by June et al., Mol. Cell Biol. 7:4472-4481 (1987).(Ab=antibodies; mAb=monoclonal antibodies). CD8⁺ T cells were purifiedidentically, but OKT8 Ab (ATCC) was substituted for the OKT4 Ab. Allcultures were maintained in AIM V (GIBCO BRL, Life Technologies, GrandIsland, N.Y.) with 3% human AB serum (BioWhittaker, Walkersville, Md.).Human IL-2 (Chiron Therapeutics, Emeryville, Calif.) was added at 20IU/mL where indicated.

T lymphocyte stimulation and long-term culture. At each time point atwhich the lymphocytes were stimulated, the K562 cell-based aAPCs wereirradiated with 10,000 rads, then washed twice into T cell culturemedium. Cell-based aAPCs were then loaded with anti-CD3 (OKT3) andanti-CD28 mAbs (9.3) at 0.5 μg/ml for 10 minutes at room temperature.Unwashed, antibody-loaded aAPCs were then mixed with CD8⁺ T cells at a1:2 K562:T cell ratio. The T cell concentration was maintained at0.5×10⁶ cells/ml throughout culture, and up to 100×10⁶ T cells weremaintained in flasks. Anti-CD3/28 bead stimulation was performed aspreviously described by Levine et al., J. Immunol. 159:5921-5930 (1997).Cultured T cells were monitored for cell volume and enumerated on aCoulter Multisizer II (Miami, Fla.) every 2-3 days, and re-stimulated at7-10 day intervals when the mean lymphocyte volume reached 200-250 fL.

Flow cytometry and FACS sorting. Cells were stained with antibodies(and/or MHC tetramers) at 4° C., and analyzed on a FACSCalibur™ (BDBioSciences, Mountain View, Calif.). Apoptosis assays were conducted perthe manufacturer's protocol (R & D Systems, Minneapolis, Minn.). Cellsorting was performed on a MoFlo® cell sorter (Cytomation, Fort Collins,Calif.). All flow cytometry data were analyzed with FlowJo software(TreeStar, San Carlos, Calif.).

Real-time PCR and TCR VB repertoire analysis. Real time PCR wasperformed and normalized to 28s rRNA levels as described previously byRiley et al., J. Immunol. 166, 4943-4948 (2001). The diversity of TCR VBrepertoire was assessed by determination of CDR3 size lengths bymultiplex PCR as previously described by Claret et al., J. Clin. Invest.100:855-866 (1997).

⁵¹Cr release assays. Target T2 cells (ATCC) were pulsed with 10 μM flupeptide (see Maus et al., 2002) or left unpulsed before labeling with⁵¹chromium (PerkinElmer Life Sciences, Inc., Boston Mass.). After afour-hour incubation of effectors with targets, radioactivity wascounted from an aliquot of supernatant. Specific lysis was calculated bystandard methods.

After a four-hour incubation of effectors with targets, radioactivitywas counted from an aliquot of supernatant. Specific lysis wascalculated by standard methods.

Example 1 Construction of Artificial APCs (aAPCs)

A cell-based aAPC was designed which could be genetically manipulated toexpress different co-stimulatory molecules in addition to CD28. K562cells were chosen because they do not express HLA proteins that wouldpromote allogeneic responses, but they do express the T cell interactionmolecules ICAM (CD54) and LFA-3 (CD58) (FIG. 1A). K562 cells expressingthe human Fcγ receptor CD32 (K32 cells) were transfected and then clonedto permit exogenous loading of anti-CD3 and anti-CD28 antibodies (FIG.1A). Similarly, the K32/4-1BBL line (FIGS. 1A, B) was generated bytransfecting K32 cells with human 4-1BB ligand. Cultures were initiatedby adding γ-irradiated aAPCs to fresh human CD8⁺ T cells prepared-bynegative selection as described.

K32 and K32/4-1BBL aAPCs efficiently activate human polyclonal CD8⁺ Tcells. The aAPCs were tested for their ability to stimulate the initialactivation and proliferation of primary CD8⁺ T cells. The T cells werestimulated with three different preparations of aAPCs: CD3/28 beads, K32cells coated with anti-CD3 and anti-CD28 (K32/CD3/28), or K32/4-1BBLcells coated with the same antibodies (K32/4-1BBL/CD3/28). The initialrate of growth of the T cells stimulated with all three aAPCs wasequivalent, as judged by thymidine incorporation (FIG. 1C). Thisobservation was confirmed by labeling fresh T cells withcarboxyfluorescein diacetate succinimidyl ester (CFSE) and tracking celldivision during the first five days of culture (data not shown). TheK562 cell-based system was found to be equivalent to CD3/28 beads forthe induction of proliferation and cell division of CD4⁺ T cells (FIG.1C and data not shown). Neither K562-based aAPCs, nor CD8⁺ T cells, norCD4⁺ T cells incubated separately showed any proliferation (FIG. 1C anddata not shown). Thus, the requirements for the initial rounds of CD8⁺ Tcell proliferation were satisfied equally by CD3/CD28 stimulationprovided in the context of polystyrene beads or cell based aAPCs, andthe addition of 4-1BBL co-stimulation did not appear to have furtherbenefit.

Example 2 K32/4-1BBL aAPCs Permit Long-Term Expansion of HumanPolyclonal CD8⁺ T Cells

Next, to determine whether the aAPC were sufficient to maintain longterm propagation of CD8⁺ T cells (FIG. 2A) CD8⁺ T cells were stimulatedwith aAPCs—but no exogenous cytokines were added to the medium. CD3/28bead-stimulated cells failed to proliferate after the second stimulationwith aAPCs, in agreement with previous findings. Similarly, CD8⁺ T cellsstimulated with CD3/28 in the context of K32 cells entered into aplateau phase of the growth curve within 2 weeks of culture, and noadditional net growth of cells occurred after re-stimulation.

In contrast, when CD8⁺ T cell cultures were stimulated withK32/4-1BBL/CD3/28 aAPCs, they remained in exponential growth even aftera third stimulation. This augmentation of long-term proliferation wasreproducible, as the average increase in the total number of T cells was410-fold higher in cultures stimulated with K32/4-1BBL/CD3/28 than incultures stimulated with CD3/28 beads in six independent experiments.

Phenotypic analysis of cultures showed a progressive enrichment for CD3⁺CD8⁺ T cells after stimulation with K32/4-1BBL/CD3/28 aAPCs (FIG. 2B).The cell based aAPCs rapidly disappeared from the cell culture, asevidenced by an inability to detect the irradiated K32/4-1BBL cells byflow cytometry after seven days (FIG. 2C). This finding was confirmed inlarge-scale experiments and also by RT-PCR for CD32 (data not shown).Thus, the mixed T cell and aAPC culture yields a population ofessentially pure T cells within one week.

Example 3 Efficient Propagation of Antigen-Specific Cytotoxic T Cells byK32/4-1BBL AAPCS

In certain embodiments, immunotherapy with CD8⁺ T cells will likelyrequire cells with antigen-specific cytolytic functions. Therefore, itwas necessary to determine whether the K32/4-1BBL aAPCs could be used toexpand antigen-specific CTLs, although antigens are not essential in thepresentation of the aAPCs. Consequently, they were used to culture apopulation of MHC tetramer sorted primary CD8⁺ T cells for 10 weeks(FIG. 3A). Purified CD8⁺ T cells obtained from an HLA-A*0201 donor werestained and sorted with an A*0201 MHC tetramer loaded with a flu matrixprotein peptide (flu MP tetramer). The tetramer⁺ population was presentat an initial frequency of 0.081% (FIG. 3B), which presumably wascomposed mainly of memory T cells. Cultures of tetramer⁻ CD8⁺ T cellsserved as an internal control population of T cells to assess the growthpotential and specificity of the tetramer⁺ population of CD8⁺ T cells.

After bulk sorting, 16,000 cells each of CD8⁺ fluMP-tetramer⁺ andtetramer⁻ phenotype were stimulated with irradiated K32/4-1BBL/CD3/28aAPCs (FIG. 3C). All cells were re-stimulated with K32/4-1BBL aAPCs at˜10 day intervals and rhIL-2 (20 IU/mL) was added to the culture duringthe 4^(th) week. No specific flu stimulation was provided duringculture. Exponential growth curves of both populations of cells wereobtained for several months. The 16,000 antigen-specific T cells yielded1.5×10⁹ cells after one month of culture, a number of cells sufficientfor immunotherapy. The substantial proliferative capacity of the CD8⁺ Tcells that remained after 30 days of culture indicated that these CTLscould have substantial long-term engraftment potential after adoptivetransfer.

To determine if antigen specificity of the expanded populations wasmaintained during culture, cells were stained with flu MP tetramer⁺(FIG. 3B). On day 17, the population that was initially sorted as flu MPtetramer⁺ was 61.7% CD8⁺ flu MP tetramer⁺, while the population that wassorted as flu MP tetramer⁻ had negligible staining. The percentage oftetramer⁺ cells in culture declined somewhat over time, but remainedat >20% through day 60 (data not shown).

Similar results were obtained with T cells from another HLAA*0201 donor,where on day 26 of culture, the population sorted as flu MP tetramer⁺was 49% CD8⁺ flu MP tetramer⁺ and again remained at >20% through day 60(data not shown). Thus, a single round of selection for CD8⁺ cells withthe desired specificity is sufficient to maintain acceptable purity ofCD8⁺ cells cultured on K32/4-1BBL/CD3/28 aAPCs.

To examine the effector function of the cultured T cells, theantigen-specific cytolytic activity of the flu MP tetramer⁺ andtetramer⁻ cultures was determined by ⁵¹Cr release assays on days 26, 30,and 56 of ex vivo expansion (FIG. 3D and data not shown). The HLA-A*0201TAP deficient T2 cell line, pulsed or unpulsed with the flu MP peptidewas used as a target population. At all time points, flu MP tetramer⁺cells displayed potent cytotoxicity for flu-MP peptide pulsed targets.Flu MP tetramer⁺ cells did not kill unpulsed targets, and the Flu MPtetramer⁻ cells did not kill either pulsed or unpulsed target cells.Neither effector population killed the parental K562 cells, suggestingthat killing was MHC-restricted, and not directed at K562 alloantigens(data not shown). Similar results were obtained with both donors (datanot shown).

Example 4 Maintenance of Diverse TCR Repertoire by K32/4-1Bbl aAPC

Given the finding that many tumor antigens are self antigens, adoptiveimmunotherapy will require the isolation and propagation of T cells withgenerally low affinity TCRs. Therefore, it is desirable that the culturesystem propagate T cells with uniform efficiency. To compare theproperties of the cultures grown with aAPCs, cultures of enriched CD8⁺ Tcells grown on anti-CD3/28 coated beads, and K32/CD3/28 andK32/4-1BBL/CD3/28 aAPCs were assessed for maintenance of the initial TCRrepertoire. CDR3 size length analysis of TCR β-chains was used becauseit permits sensitive detection of clonal T cell outgrowth.

It has been previously shown by the inventors that CD3/28 coated beadscan maintain diverse CD4⁺ T cell populations for several months inculture. However, dramatic perturbations of the input CD8⁺ repertoireoccurred after two weeks of culture on these beads. In contrast,enriched CD8⁺ T cells cultured on K32/4-1BBL/CD3/28 aAPC maintained CDR3size length distributions that were similar to the input population of Tcells (FIG. 4). The addition of 4-1BBL appeared to account for thepreservation of the repertoire, because cultures of enriched CD8⁺ Tcells on K32/CD3/28 aAPC did not maintain a comparably diverserepertoire (FIG. 4).

Example 5 K32/4-1BBL aAPC Stimulation Enhances Survival of Human CD8⁺ TCells Upon Re-Stimulation

Because the initial growth rate of CD8⁺ T cells stimulated with threedifferent aAPCs was similar, it appeared that the increased overallgrowth observed in K32/4-1BBL/CD3/28 stimulated T cells was due toimproved survival. Therefore, a determination was made of the relativeeffects of the various aAPCs on Bcl-xL and IL-2 expression, two genesinvolved in T cell survival and proliferation, respectively.

Quantitative real time RT-PCR was used to determine the levels ofsteady-state mRNA coding for Bcl-xL and IL-2 (FIG. 5). In all cultures,Bcl-xL and IL-2 gene expression was upregulated compared to restingcells one and three days after the first stimulation, and by day 10,Bcl-xL and IL-2 gene expression had returned to resting levels. However,one to three days after re-stimulation, only CD8⁺ T cell cultures thatwere stimulated with the K32/4-1BBL/CD3/28 aAPCs had increased levels ofBcl-xL and IL-2 mRNA. In contrast, CD8⁺ T cells that were stimulatedwith beads or K32/CD3/28 cells did not re-induce Bcl-xL or IL-2expression after a second stimulation (FIGS. 5A and B, respectively).Together these data suggest that 4-1BB co-stimulation provides asurvival signal that is critical for subsequent but not the initialstimulation of CD8⁺ T cell proliferation.

The viability was assessed of the CD8⁺ T cells stimulated by the variousaAPCs during culture by fluorescent staining with annexin V andpropidium iodide (FIG. 6). In the bead-stimulated cultures, viabilitygradually decreased in the first ten days, and then droppedprecipitously as only 6% of cells were viable on day 20. In the T cellcultures stimulated with K32 aAPCs, T cell viability seven days afterthe second stimulation was improved compared to bead-stimulated cells.However, most of the cells died by day 20.

In contrast, K32/4-1BBL/CD3/28 stimulated CD8⁺ T cell cultures were >70%viable throughout culture. Together these results show that the additionof 4-1BBL co-stimulation prevents apoptosis and preserves the startingrepertoire of CD8⁺ T cells.

In sum, the K562 cell based aAPC system is able to maintain long termexponential growth of viable T cells, particularly CD8⁺ memory cells formany months in vitro. Based on a starting cell population of 1 influenzaspecific CD8³⁰ T cells, a sufficient number of CTL were obtained fortherapy after only 30 days of culture. Since the starting number ofantigen specific CD8⁺ T cells could be isolated from only 100 ml ofblood, given an initial frequency of 0.05%, it would be possible todecrease the culture time to only two weeks by performing aleukapheresis and isolating 10⁵ to 10⁶ antigen-specific CD8⁺ T cells.High speed cell sorting or magnetic bead separation can isolatesufficient CD8⁺ memory cells for initial culture on K32/4-1BBL aAPCcoated with anti-CD3 and CD28 antibodies. Alternatively, it is possibleto coat the K32/4-1BBL aAPC with the desired tetramer in order toculture antigen specific T cells de novo, and obviate the need for aseparate cell isolation procedure. The flexibility of the present systemis particularly advantageous, in that the engineering of the aAPC can bemodified and focused based upon the specific T cell need.

One implication of the present system is that the CTLs retain asubstantial replicative capacity after culture with theK32/4-1BBL/CD3/28 aAPCs, even after reaching therapeutic numbers forclinical infusion. Several mechanisms appear to account for the improvedgrowth and repertoire of K32/4-1BBL/CD3/28 stimulated CD8⁺ T cells. Forinstance, as noted, there was a markedly improved survival of CD8⁺ Tcells after repeated stimulation with K32/4-1BBL/CD3/28 aAPC, ascompared with CD3/28 coated beads. With the addition of 4-1BBco-stimulation, CD8⁺ T cells have increased expression of IL-2 andBcl-xL, improved survival, and continued proliferation afterre-stimulation with anti-CD3/CD28. Thus, 4-1BB stimulation in thiscontext overcomes the previously described activation-inducednon-responsiveness.

Not all clinically useful antigens are presently characterized asMHC-restricted epitopes, and the library of MHC tetramers for many HLAtypes remains limiting. Therefore, K32/4-1BBL/CD3/28 aAPCs were alsoused to expand CTLs that have been previously enriched for a particularantigen-specificity by priming with autologous DC that have been pulsedwith apoptotic bodies of autologous tumor (unpublished data). Thus,K32/4-1BBL/CD3/28 aAPCs are likely to be complementary to many methods,including MHC tetramer sorting (Dunbar et al., Curr. Biol. 8:413-416(1998); Yee, et al., J. Immunol. 162:2227-2234 (1999)), or priming withautologous DCs or other artificial APCs (Latouche et al., 2000), thatenrich for antigen-specific CTL populations. Although thus far theK32/4-1BBL/CD3/28 aAPCs have been tested for their ability to expandmemory or primed T cells; they and other APC constructs will be usefulto expand naive CD8⁺ cells as a source of the ‘self’ repertoire fortumor immunotherapy (Curtsinger et al., J. Immunol. 160:3236-3243(1998); Sagerstrom et al., Proc. Natl. Acad. Sci. USA 90:8987-8991(1993); Wang et al., J. Immunol. 164:1216-1222 (2000).

Expanding low-avidity, self-reactive T cells Voltz et al., N. Engl. J.Med. 340:1788-1795 (1999) that can differentiate into memory cells (Tan,J. Clin. Invest. 108:1411-1415 (2001)) offers a useful approach toderive therapeutic numbers of self reactive CTLs. Advantageously,because only T cells that recognize the MHC/peptide complex areactivated in the present invention, rapid expansion is provided forselected antigen specific clones. Once characterized, these cell lineswill be invaluable tools for immunotherapy, particularly since the celllines permit the design of optimal co-stimulation regimes on adisease-by-disease basis. Moreover, given that GMP preparations ofanti-CD3 and CD28 antibodies are currently available, and thatK32/4-1BBL aAPC can be grown in serum free medium, the system of thepresent invention provides therapeutic resources for clinical adoptiveimmunotherapy, for patients with cancer and viral diseases, as well asfor the in vitro propagation of CTLs for experimentation. Finally, inlight of the many co-stimulatory molecules that continue to bediscovered, e.g., OX40L, CD40, CD80, CD86, GL50, 4-1BBL and B7-H1, thatserve to either augment the level of T cell growth or alter thefunctional ability of the T cells, the present invention offers novelmethods by which the usefulness of these additional co-stimulators canbe evaluated as immunotherapeutic agents by transfecting them into K-32cells and testing their effect on overall T cell growth and infunctional assays.

Example 6 K32 aAPCs with and without CD86 Permit Long-Term Expansion ofHuman Polyclonal CD4⁺ T Cells

Construction and initial testing of K32 aAPCs with and without CD86: Wewanted to design an artificial APC (aAPC) that would allow the rapidexpansion of human CD4 T cells in an antigen and MHC independent manner.To evaluate different human cell lines in their ability to stimulate CD4T cell growth, we transfected K562 and U937 cells with CD32 with andwithout CD86 to create K32, U32 and K32/86 cell lines. Both of thesemyelogenous leukemia cell lines grow in suspension and the transition ofK562 cells, in particular, to clinical trials will be expedited becausethey do not express MHC molecules that would promote an allogenicresponse, can easily be killed by natural killer (NK) cells, and growwell in serum free conditions.

To initially characterize the ability of these cell lines to stimulate Tcell proliferation, we performed a standard [³H]-thymidine incorporationassay. Irradiated K32+anti-CD3 and CD28 Abs (K32/CD3/28), U32+anti-CD3and CD28 Abs (U32/CD3/28), K32/86+anti-CD3 Ab cells (K32/86/CD3) andanti-CD3 and CD28 Abs coated beads (CD3/28 coated beads) were used tostimulate freshly isolated human CD4 T cells and [³H]-thymidineincorporation was measured after three days of culture. All cell basedaAPC stimulated cultures demonstrated higher [³H]-thymidine uptake thanthe cells stimulated with CD3/28 coated beads demonstrating that at thelevel of inducing T cell proliferation, cell based expansion systemswere more potent than the bead based system. Control cultures in whichthe anti-CD3 and anti-CD28 Ab were left out demonstrated minimal(background) levels of [³H]-thymidine, indicating that CD4 T cellsrather than the irradiated stimulator cells were responsible for the[³H]-thymidine uptake. K32/CD3/28 and CD3/28 coated bead stimulatedcells continued to grow exponentially for ten days withoutrestimulation. Additionally, CD4 T cells stimulated with K32/CD3/28 orK32/CD3/86 underwent on average two more population doublings within thefirst ten days indicating that it is a more rapid T cell expansionsystem than the CD3/28 coated beads.

For optimal engraftment potential and possible therapeutic benefit, itis important to ensure that the T cells, after in vitro expansion, arefunctional and not senescent at the time of re-infusion. To test whetherCD4 T cells expanded by K32/CD3/28 aAPCs were able to produce cytokinesand survival factors upon restimulation, fresh CD4 T cells werestimulated with either K32/CD3/28 or CD3/28 coated beads and allowed toexpand for 10 days. Three days after restimulation, RNA was harvestedand cytokine production was measured by quantitative RT-PCR. We observedthat CD4 T cells restimulated with K32 CD3/28 could induce a wide arrayof cytokines (IL-2, IL-10, and IFNγ), a costimulatory, molecule (ICOS)and a cell survival factor (Bclx-L) in all cases greater than or equalto as cells stimulated with CD3/28 coated beads.

Furthermore, log linear growth of CD4 T cells was maintained for atleast 45 days using the K32/CD3/28, K32/86/CD3 and CD3/28 coated beadexpansion systems with all of the cultures undergoing at least two morerestimulations demonstrating K32 CD3/28 stimulated cells have thecapacity to expand far beyond what is required for immunotherapy trials.At the end of 45 days of culture the K32/CD3/28 stimulated CD4 T cellshad undergone 26 population doublings (6.7×10⁷ fold expansion, data notshown). These studies demonstrate that rapid expansion of CD4 T cellscan be achieved using K32/CD3/28 aAPCs and suggest that once these cellsare infused back into the patient, they will be at least as functionalas CD4 T cells stimulated by CD3/28 coated beads.

One possible use of ex vivo expanded polyclonal T cells is toreconstitute the immune system of immunodeficient individuals. For thistherapy to be successful, gaps in the T cell repertoire must not becreated by selective expansion of certain T cell subtypes. As describedabove in Example 4, using Vβ T cell repertoire analysis it was foundthat CD8⁺ T cells expanded with K32/4-BBL/CD3/28 were not skewed to anyparticular Vβ family. These findings were extended using a backcalculation method described by Wells et al (Wells, A. D.,Gudmundsdottir, H., and Turka, L. A., Following the fate of individual Tcells throughout activation and clonal expansion. Signals from T cellreceptor and CD28 differentially regulate the induction and duration ofa proliferative response. J. Clin. Invest 100, 3173-3183, 1997) thatmeasures the number of cells under each peak to determine the percentageof cells that never divided. Table 1 below shows the calculationsperformed to elucidate what percentage of the resting CD4 T cellsstimulated with either K32/CD3/28 or CD3/28 coated beads that divided.Our results from this analysis indicate that upon optimal stimulationwith an aAPC the vast majority (95% for K32/CD3/28 and 90% for CD3/28coated bead stimulated cells) of all human CD4⁺ T cells can divide.

TABLE 1 K32/CD3/28 CD3/28 Coated Beads % of Starting % of Starting TotalAbsolute Population in Absolute Population in Division Number Number ofEach Total Number Number of Each Division Peak of Cells PrecursorsDivision Peak of Cells Precursors Peak 0 106 106 5 213 213 10 1 555 27814 916 458 22 2 2506 626 31 2322 580 28 3 5144 643 32 3694 462 22 4 5466342 17 5534 346 16 5 558 17 1 1519 47 2

Table Legend: The vast majority of human CD4 T cells divide upon optimalstimulation. CD4 T cells were labeled with CFSE and stimulated witheither K32/CD3/28 or CD3/28 coated beads as described above. After fourdays of stimulation, the number of cells under each division peak wasdetermined using Flow-Jo software. The absolute number of precursors wasdetermined by dividing the total number of cells by 2^(n) where n=thenumber of divisions (division peak). The percentage of startingpopulation in each division peak was determined by dividing the absolutenumber of precursors by the total number of absolute precursors (2012,for K32/CD3/28 and 2016 for CD3/28 coated beads) (Wells, A. D.,Gudmundsdottir, H., and Turka, L. A.). Following the fate of individualT cells throughout activation and clonal expansion. Signals from T cellreceptor and CD28 differentially regulate the induction and duration ofa proliferative response. J. Clin. Invest 100, 3173-3183, 1997).

Example 7 Co-Culture with CD3/28 Activated CD4⁺ T Cells InducesUpregulation of mRNA Encoding for IL-15, B7-H1, B7-D and B7-H3 in K32aAPC

Co-culture with CD3/28 activated CD4⁺ T cells induces upregulation ofmRNA encoding for IL-15, B7-H1, B7-D and B7-H3 in K32. Molecules thatwere preferentially expressed in K32 cells but not U32 cells that mayaccount for their differences to serve as aAPCs and to augment IL-2production. We hypothesized that crosstalk between K32/CD3/28 aAPCs andthe recently activated CD4⁺ T cells were inducing the expression ofcostimulatory molecules on the irradiated K32 cells. Therefore, weassayed for the expression of molecules in the aAPC/CD4 mixtures in thepresence or absence of anti-CD3 and anti-CD28 antibodies, allowing us tocompare expression of costimulatory molecules and cytokines in thepresence or absence of activated CD4⁺ T cells. Li et al, demonstratedthat IL-15 is critical for the onset of T cell division in a murinemodel (Li, X. C., et al., T cell Nat. Med. 7, 114-118, 2001.), making ita candidate responsible for the early onset of cell division inK32/CD3/28 aAPCs stimulated CD4⁺ T cells. K32 cells constitutivelyexpress low levels of mRNA encoding for IL-15. After coculture withactivated CD4⁺ T cells, IL-15 mRNA was upregulated 15-fold. U32 cellsdid not express IL-15 mRNA either constitutively or after incubationwith activated CD4 T cells. In addition to cytokines, differentialexpression of costimulatory cell surface molecules could also accountfor the differences in stimulatory capacities between K32 and U32 aAPCs.We did not detect expression of Ox40L or B7-H1 (ICOS ligand) by RT-PCRin either K32 or U32. Using flow cytometry, we were unable to detectexpression of CD80 or 41BB-L on either K32 or U32 and could not detectCD86 on K32 cells. U32 cells express low levels of CD86. K562 cells doexpress high levels of ICAM-1 and LFA-3 (Maus, M. V., Thomas, A. K.,Leonard, D. G, Allman, D., Addya, K., Schlienger, K., Riley, J. L., andJune, C. H., Ex vivo expansion of polyclonal and antigen-specificcytotoxic T lymphocytes by artificial APCs expressing ligands for the Tcell receptor, CD28 and 4-1BB. Nat. Biotechnol. 20, 143-148, 2002), butblocking experiments with monoclonal antibodies specific for both ICAM-1and LFA-3 failed to diminish CD4 cell proliferation, demonstrating thatthese adhesion molecules are not required for the strong T cellstimulation by K32 cells.

Next, we searched for expression of newly described costimulatorymolecules PD-L1, PD-L2 and B7-H3, whose role in human T cell activationhas not been clearly established. While we did not detect constitutiveexpression PD-L1 in K32, U32, or resting CD4⁺ T cells, we did observea >45 fold upregulation of PD-L1 mRNA K32/CD3/28 stimulated CD4 Tcultures that was not observed in U32/CD3/28 stimulated culture.Likewise, we found a low level of PD-L2 mRNA in resting K32 cells thatwas modestly upregulated upon K32/CD3 stimulation. Much higherquantities of PD-L2 mRNA were observed in K32/CD3/28 stimulatedcultures. Minimal PD-L2 expression was detected in CD4⁺ T cells mixedwith U32/CD3 or U32/CD3/28 aAPCs.

Lastly, we searched for expression of another recently describedcostimulatory molecule, B7-H3 (Chapoval, A. I., Ni, J., Lau, J. S.,Wilcox, R. A., Flies, D. B., Liu, D., Dong, H., Sica, G. L., Zhu, G.,Tamada, K., and Chen, L., B7-H3: a costimulatory molecule for T cellactivation and IFN-gamma production. Nat. Immunol. 2, 269-274, 2001.).Unlike PD-L1 and PD-L2, B7-H3 was constitutively expressed severalthousand-fold over resting CD4⁺ T cells in K32 cells as compared to U32aAPCs. Coculture with anti-CD3 and/or anti-CD28 did not significantlychange B7-H3 expression in K562 cells suggesting it is unlikely to be areason K32/CD3/28 stimulated CD4⁺ T cells expand longer than K32/CD3activated CD4⁺ T cells; however, it could explain why K32/CD3 aAPC (i.e.anti-CD28 deficient aAPC) can induce CD4⁺ T cells to produce IL-2 andexpand. To demonstrate that, in fact, the K32 cells were expressingIL-15, PD-L1, PD-L2 and B7-H3 rather than the CD4⁺ T cells, we treatedirradiated K32 with supernatant from T cells activated with K32/CD3/28or CD3/28 coated beads. We observed similar levels of induction of IL-15and PD-L1 in K32 cells stimulated with supernatants from K32/CD3/28 orCD3/28 bead activated T cells demonstrating that cell contact betweenthe K562 cell and the T cell is not necessary for the upregulation ofthese molecules and soluble factors can substitute for activated Tcells. B7-H3 was only modestly upregulated in K32 cells after incubationwith supernatant from K32/CD3/28 stimulated T cells consistent withminimal upregulation observed. PD-L2 was only slightly induced on K32cells after incubation with T cell supernatant suggesting that eithercell-to-cell contact is necessary to upregulate PD-L2 or a substantialfaction of the PD-L2 mRNA upregulation occurred in the T cells. Theunexpected expression of these recently described costimulatory ligandsin K32 cells may contribute their potency as aAPC.

Example 8 K32/4-1 BBL aAPC Driven Expansion of hTERT-Specific CTLs forAdoptive Immunotherapy

In this example, K32/4-1BBL/CD3/28 aAPCs were used to expand humantelomerase reverse transcriptase (hTERT)-specific CTLs.

In a Phase I study, advanced breast and prostate cancer patients werevaccinated with 5×10⁶ dentritic cells (DC) pulsed with the hTERT 1540epitope. Following 6 subcutaneous vaccinations, every other week,immunological responses were evaluated using proliferation assays, MHCclass I tetramer analysis of specific T cells, ELISPOT analysis, andchromium release assays. Although undetectable at baseline,hTERT-specific CTL were identified after vaccination by tetramerstaining in 4 patients, ranging from 0.26% to 0.58% tetramer⁺CD8⁺ cellsin uncultured peripheral blood and up to 6.3% tetramer⁺CD8⁺ cells after7 days of in vitro peptide stimulation. These hTERT-specific CTLsecreted IFN-γ when challenged during ELISPOT analysis with hTERTpeptide but not a negative control peptide, whereas no IFN-γ secretinghTERT-specific cells were identified prior to vaccination. These CTLwere functional as shown by the fact that they lysed tumor cells in anMHC-restricted fashion, including HLA-A2⁺, hTERT⁺ carcinoma cells, butnot HLA-A2-negative, hTERT⁺ cells.

Additionally, as shown in FIG. 7, a nearly pure population of tetramer⁺hTERT-specific CD8⁺ cells were generated from post-vaccine patientsamples after 2 rounds of tetramer sorting and expansion usingK32/4-1BBL/CD3/28 aAPCs. These hTERT-specific T cells secrete IFN-γ inresponse to hTERT peptide and lyse HLA-A2⁺, telomerase-positivecarcinoma cells but not HLA-A2-negative, telomerase-positive cells.Cellular expansion was extensive—more than 18 population doublings over50 days in each of the 2 donors tested. Thus, tetramer-guided CD8⁺ Tcell expansion in this system generates large numbers of polyclonal andfunctional tumor antigen-specific CD8⁺ T cells ex vivo, suggesting aplatform for the design of TERT-specific adoptive T cell therapy inwhich TERT-specific T cells are first induced in vivo by vaccinationthen expanded ex vivo under optimized costimulatory conditions forsubsequent re-infusion.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in the Application Data Sheet, including but not limited to U.S.patent application Ser. No. 09/960,264, filed Sep. 20, 2001; which is acontinuation-in-part of U.S. application Ser. No. 09/794,230, filed Feb.26, 2001; which claims the benefit of Provisional Application No.60/184,788, filed Feb. 24, 2000, and 60/249,902, filed Nov. 17, 2000,are incorporated herein by reference, in their entirety.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims. All of references, patents,patent applications, etc. cited above, are incorporated herein in theirentirety. Further, all numerical ranges recited herein explicitlyinclude all integer values within the range.

1. An in vitro method for activating or stimulating a population of Tcells, the method comprising: contacting said population of cells withan engineered K562 cell followed by restimulation of said T cells withsaid engineered K562 cell, wherein said engineered K562 cellcomprises: 1) an exogenous antibody that binds to CD3 or CD2, whereinthe antibody is loaded onto a human Fcγ receptor wherein the Fcγreceptor is expressed from an expression vector in said engineered K562cell, 2) a molecule that binds CD28 selected from the group consistingof anti-CD28 antibody, CD80, and CD86, and 3) 4-1BBL; therebystimulating or activating said T cells.
 2. The method of claim 1,further comprising in vitro expanding said T cells by incubating in thepresence of said engineered K562 cell.
 3. The method of claim 1, furthercomprising separating said T cell from said engineered K562 cell andsubsequently incubating said T cells in vitro with an agent thatfacilitates T cell expansion.
 4. The method of claim 1, wherein said Tcells are a T cell line.
 5. The method of claim 1, wherein said T cellsare a T cell clone.
 6. An in vitro method for maintaining T cellrepertoire, the method comprising providing a population of T cells withan engineered K562 cell for a time sufficient to induce activation andsubsequently expanding said T cells followed by restimulation of said Tcell with said engineered K562 cell, thereby maintaining said T cellrepertoire, wherein said engineered K562 cell comprises: 1) an exogenousantibody that binds to CD3 or wherein the antibody is loaded onto ahuman Fcγ receptor wherein the Fcγ receptor is expressed from anexpression vector in said engineered K562 cell, 2) a molecule that bindsCD28 selected from the group consisting of anti-CD28 antibody, CD80, andCD86, and 3) 4-1BBL, thereby maintaining said T cell repertoire.
 7. Themethod of claim 6, further comprising in vitro expanding said T cells byincubating said T cells in the presence of said engineered K562 cell. 8.A method for maintaining the viability of T cells during culture, themethod comprising contacting said T cells with an engineered K562 cellfollowed by restimulation of said T cells with said engineered K562cell, wherein said engineered K562 cell comprises: 1) an exogenousantibody that binds to CD3 or wherein the antibody is loaded onto ahuman Fcγ receptor wherein the Fcγ receptor is expressed from anexpression vector in said engineered K562 cell, 2) a molecule that bindsCD28 selected from the group consisting of anti-CD28 antibody, CD80, andCD86, and 3) 4-1BBL, thereby maintaining the viability of said T cellsduring culture.
 9. The method of claim 8, wherein said T cells are CD4⁺T cells.
 10. The method of claim 8, wherein said T cells are CD8⁺ Tcells.
 11. The method of claim 8, wherein said contacting occurs bysequential stimulation of T cells by said engineered K562 cell.
 12. Anin vitro method for expanding a population of T cells, the methodcomprising: contacting said population of T cells with an engineeredK562 cell followed by restimulation of said T cells with said engineeredK562 cell, wherein said engineered K562 cell comprises: 1) an exogenousantibody that binds to CD3 or wherein the antibody is loaded onto ahuman Fcγ receptor wherein the Fcγ receptor is expressed from anexpression vector in said engineered K562 cell, 2) a molecule that bindsCD28 selected from the group consisting of anti-CD28 antibody; and 3)4-1BBL; and culturing said T cells under conditions and time sufficientto induce cell division, wherein said contacting occurs in the absenceof exogenously added cytokines, thereby expanding said population of Tcells.
 13. The method of claim 12, further comprising sequentiallystimulating said T cells in vitro with said engineered K562 cell eitherby previously purifying T cells from originally added engineered K562cell and subsequently adding additional engineered K562 cell or byadding additional engineered K562 cell to previously stimulated cellswithout separation of originally added engineered K562 cell from saidpreviously stimulated cells.
 14. The method of claim 12, furthercomprising separating said T cells from said engineered K562 cell andsubsequently incubating said T cells with an agent that facilitates Tcell expansion, followed by restimulation of said T cells with saidengineered K562 cell in vitro.
 15. An in vitro method for expanding apopulation of T cells, said method comprising: contacting saidpopulation of T cells with an engineered K562 cell followed byrestimulation of said T cells with said engineered K562 cell, whereinsaid engineered K562 cell comprises: 1) an exogenous antibody that bindsto CD3 or wherein the antibody is loaded onto a human Fcγ receptorwherein the Fcγ receptor is expressed from an expression vector in saidengineered K562 cell, 2) a molecule that binds CD28 selected from thegroup consisting of anti-CD28 antibody, CD80, CD86; and 3) 4-1BBL; andculturing said T cells under conditions and time sufficient to inducecell division thereby expanding said population of T cells.
 16. Themethod of claim 15, further comprising sequentially stimulating said Tcells in vitro with said engineered K562 cell either by previouslypurifying T cells from originally added engineered K562 cell andsubsequently adding additional engineered K562 cell or by addingadditional engineered K562 cell to previously stimulated cells withoutseparation of originally added engineered K562 cell.
 17. The method ofclaim 15, further comprising separating said T cells from saidengineered K562 cell and subsequently incubating said T cells with anagent that facilitates T cell expansion, followed by restimulation withsaid engineered K562 cell in vitro.
 18. The method of claim 15, whereinfollowing initial stimulation or activation said T cells are separatedfrom said engineered K562 cell and then expanded in vitro in thepresence of exogenously added cytokines.
 19. The method of claim 18,wherein said T cells are substantially free of said engineered K562 cellprior to in vitro expansion.
 20. An ex vivo method for expanding antigenspecific T cells, the method comprising: a. contacting a population of Tcells with an antigen for a time sufficient to induce activation of Tcells specific to said antigen; and b. contacting said population ofantigen-specific T cells ex vivo with an engineered K562 cell underconditions and for time sufficient to induce proliferation of saidantigen-specific T cells followed by restimulation of said T cells withsaid engineered K562 cell, wherein said engineered K562 cellcomprises: 1) an exogenous antibody that binds to CD3 or CD2, whereinthe antibody is loaded onto a human Fcγ receptor wherein the Fcγreceptor is expressed from an expression vector in said engineered K562cell, 2) a molecule that binds CD28 selected from the group consistingof anti-CD28 antibody, CD80, and CD86; and 3) 4-1BBL, thereby expandingsaid antigen specific T cells.
 21. An in vitro method of activatingantigen specific T cells, the method comprising contacting T cells withan antigen and an engineered K562 cell under conditions and for timesufficient to induce activation of T cells specific to said antigenfollowed by restimulation of said T cells with said engineered K562cell, wherein said engineered K562 cell comprises: 1) an exogenousantibody that binds to CD3 or CD2, 2) a molecule that binds CD28selected from the group consisting of anti-CD28, CD80, and CD86; and 3)4-1BBL, thereby activating said antigen specific T cells.
 22. The methodof claim 21, wherein said antigen is a tumor antigen.
 23. The method ofclaim 22, wherein said antigen is human telomerase reverse transcriptase(hTERT).
 24. The method of claim 21, wherein said antigen is pulsed onor expressed by an antigen-presenting cell.
 25. The method of claim 21,further comprising at least one in vitro round of peptide-MHC tetramersorting of said antigen-specific T cells.
 26. The method of claim 21,further comprising at least one in vitro round of peptide-MHC tetramermagnetic selection of said antigen-specific T cells.